diff --git a/classes/helper/datafield_manager.php b/classes/helper/datafield_manager.php
index 32e9de0..71fa316 100644
--- a/classes/helper/datafield_manager.php
+++ b/classes/helper/datafield_manager.php
@@ -162,13 +162,8 @@ public function render_datafields($templatestr, $event = null, $stepresults = nu
 
                 return $value;
             } else {
-                // If there is no value, return the empty value.
-                if (preg_match('/\{.*?\}/', $matches[0])) {
-                    return '';
-                } else {
-                    // No match! Leave the template string in place.
-                    return $matches[0];
-                }        
+                // No match! Leave the template string in place.
+                return $matches[0];
             }
         };
 
diff --git a/classes/steps/actions/webservice_action_step.php b/classes/steps/actions/webservice_action_step.php
index b646ada..f937316 100644
--- a/classes/steps/actions/webservice_action_step.php
+++ b/classes/steps/actions/webservice_action_step.php
@@ -111,7 +111,7 @@ private function run_function() {
         $params = $this->render_datafields($this->params);
 
         // Execute the provided function name passing with the given parameters.
-        $response = self::call_external_function($functionname, json_decode($params, true));
+        $response = external_api::call_external_function($functionname, json_decode($params, true));
         return $response;
     }
 
@@ -150,12 +150,11 @@ public function execute($step, $trigger, $event, $stepresults) {
         try {
             $response = $this->run_function();
             if ($response['error']) {
-
-                // Throw an error if step results are not being returned.        
-                $stepresults['error'] = json_encode($response['exception']);
-
-                return [false, $stepresults];
+                // Throw an exception to be propagated for proper error capture.
+                throw new \coding_exception(json_encode($response['exception']));
             }
+
+            $status = [true, $response];
         } catch (\Throwable $e) {
             // Restore the previous user to avoid any side-effects occuring in later steps / code.
             \core\session\manager::set_user($previoususer);
@@ -175,8 +174,8 @@ public function execute($step, $trigger, $event, $stepresults) {
         \core\session\manager::set_user($previoususer);
         $SESSION = $session;
 
-        // Return stepresults.
-        return [true, $stepresults];
+        // Return the function call response as is. The shape is already normalised.
+        return $status;
     }
 
     /**
@@ -202,12 +201,6 @@ public function form_definition_extra($form, $mform, $customdata) {
         $mform->addElement('textarea', 'params', get_string('webserviceactionparams', 'tool_trigger'), $attributes);
         $mform->setType('params', PARAM_RAW_TRIMMED);
         $mform->addHelpButton('params', 'webserviceactionparams', 'tool_trigger');
-
-        // Params.
-        $attributes = ['cols' => '50', 'rows' => '5'];
-        $mform->addElement('textarea', 'alphaparams', get_string('webserviceactionalphaparmas', 'tool_trigger'), $attributes);
-        $mform->setType('alphaparams', PARAM_RAW_TRIMMED);
-        $mform->addHelpButton('alphaparams', 'webserviceactionalphaparmas', 'tool_trigger');
     }
 
     /**
@@ -257,14 +250,9 @@ public function form_validation($data, $files) {
 
                 $errorfield = 'params';
 
-                $alphaparams = explode(',', $data['alphaparams']);
-                // Fill template fields with a number. Some params are special and only allow letters.
-                $transformcallback = function($matches) use($alphaparams) {
-                    if (in_array($matches[1], $alphaparams)) {
-                        return '';
-                    } else {
-                        return 0;
-                    }
+                // Fill template fields with a number.
+                $transformcallback = function() {
+                    return 0;
                 };
 
                 // Cannot use redner_datafields since we need to know of the
@@ -336,106 +324,4 @@ public function transform_form_data($data) {
         }
         return $data;
     }
-
-    /**
-     * Call an external function validating all params/returns correctly.
-     *
-     * Note that an external function may modify the state of the current page, so this wrapper
-     * saves and restores tha PAGE and COURSE global variables before/after calling the external function.
-     * This is a fork of the external_api::call_external_function method.
-     * Due the nature of the WS API, without a real user session the function may not work as expected.
-     *
-     * @param string $function A webservice function name.
-     * @param array $args Params array (named params)
-     * @param boolean $ajaxonly If true, an extra check will be peformed to see if ajax is required.
-     * @return array containing keys for error (bool), exception and data.
-     */
-    public static function call_external_function($function, $args, $ajaxonly=false) {
-        global $PAGE, $COURSE, $CFG, $SITE;
-
-        require_once($CFG->libdir . "/pagelib.php");
-
-        $externalfunctioninfo = \external_api::external_function_info($function);
-
-        // Eventually this should shift into the various handlers and not be handled via config.
-        $readonlysession = $externalfunctioninfo->readonlysession ?? false;
-
-        if (!$readonlysession || empty($CFG->enable_read_only_sessions)) {
-            \core\session\manager::restart_with_write_lock($readonlysession);
-        }
-
-        $currentpage = $PAGE;
-        $currentcourse = $COURSE;
-        $response = array();
-
-        try {
-            // Taken straight from from setup.php.
-            if (!empty($CFG->moodlepageclass)) {
-                if (!empty($CFG->moodlepageclassfile)) {
-                    require_once($CFG->moodlepageclassfile);
-                }
-                $classname = $CFG->moodlepageclass;
-            } else {
-                $classname = 'moodle_page';
-            }
-
-            $PAGE = new $classname();
-            $COURSE = clone($SITE);
-
-            // Validate params, this also sorts the params properly, we need the correct order in the next part.
-            $callable = array($externalfunctioninfo->classname, 'validate_parameters');
-
-            $params = call_user_func($callable,
-                                     $externalfunctioninfo->parameters_desc,
-                                     $args);
-
-            $params = array_values($params);
-            // Allow any Moodle plugin a chance to override this call. This is a convenient spot to
-            // make arbitrary behaviour customisations. The overriding plugin could call the 'real'
-            // function first and then modify the results, or it could do a completely separate
-            // thing.
-            $callbacks = get_plugins_with_function('override_webservice_execution');
-            $result = false;
-
-            foreach ($callbacks as $plugintype => $plugins) {
-                foreach ($plugins as $plugin => $callback) {
-                    $result = $callback($externalfunctioninfo, $params);
-                    if ($result !== false) {
-                        break 2;
-                    }
-                }
-            }
-
-            // If the function was not overridden, call the real one.
-            if ($result === false) {
-                $callable = array($externalfunctioninfo->classname, $externalfunctioninfo->methodname);
-                $result = call_user_func_array($callable, $params);
-            }
-
-            // Validate the return parameters.
-            if ($externalfunctioninfo->returns_desc !== null) {
-                $callable = array($externalfunctioninfo->classname, 'clean_returnvalue');
-                $result = call_user_func($callable, $externalfunctioninfo->returns_desc, $result);
-            }
-
-            $response['error'] = false;
-            $response['data'] = $result;
-        } catch (\Throwable $e) {
-            $exception = get_exception_info($e);
-            unset($exception->a);
-            $exception->backtrace = format_backtrace($exception->backtrace, true);
-            if (!debugging('', DEBUG_DEVELOPER)) {
-                unset($exception->debuginfo);
-                unset($exception->backtrace);
-            }
-            $response['error'] = true;
-            $response['exception'] = $exception;
-            // Do not process the remaining requests.
-        }
-
-        $PAGE = $currentpage;
-        $COURSE = $currentcourse;
-
-        return $response;
-    }
 }
diff --git a/lang/en/tool_trigger.php b/lang/en/tool_trigger.php
index b12951e..e689ae9 100644
--- a/lang/en/tool_trigger.php
+++ b/lang/en/tool_trigger.php
@@ -292,8 +292,6 @@
 
 $string['webserviceactionfunctionname'] = 'Function';
 $string['webserviceactionfunctionname_help'] = 'The webservice function to be called. See the <a href="/admin/webservice/documentation.php">API Documentation</a>';
-$string['webserviceactionalphaparmas'] = 'WS alpha parameters';
-$string['webserviceactionalphaparmas_help'] = 'The form validation may fail due to some ws parameters type, if you are getting an "ALPHA" type error, add the parameter here.';
 $string['webserviceactionusername'] = 'Who';
 $string['webserviceactionusername_help'] = 'The user (username) who this step will be performed in the context of. This defaults to the main admin user if not explicitly set';
 $string['webserviceactionparams'] = 'Parameters';
diff --git a/tests/course_lookup_step_test.php b/tests/course_lookup_step_test.php
index ac21c1c..b8ee165 100644
--- a/tests/course_lookup_step_test.php
+++ b/tests/course_lookup_step_test.php
@@ -90,6 +90,35 @@ public function test_execute_basic() {
         $this->assertEquals($context->id, $stepresults['course_contextid']);
     }
 
+    /**
+     * Basic test, but this time with additional custom course field.
+     */
+    public function test_execute_basic_with_custom_profile_fields() {
+        // Create custom course field.
+        $customfieldg = $this->getDataGenerator()->get_plugin_generator('core_customfield');
+        $category  = $customfieldg->create_category();
+        $customfield = $customfieldg->create_field([
+            'categoryid' => $category->get('id'),
+            'type' => 'text',
+            'shortname' => 'testfield1',
+            'configdata' => [],
+        ]);
+
+        // Add data to the customfield_data table.
+        $this->add_course_custom_course_field_data($customfield->get('id'), $this->course->id, 'CourseFieldValue');
+        $step = new \tool_trigger\steps\lookups\course_lookup_step(
+            json_encode([
+                'courseidfield' => 'objectid',
+                'outputprefix' => 'course_'
+            ])
+        );
+
+        list($status, $stepresults) = $step->execute(null, null, $this->event, []);
+        $this->assertTrue($status);
+        // Check that the custom field data is returned as a step result.
+        $this->assertEquals('CourseFieldValue', $stepresults['course_testfield1']);
+    }
+
     /**
      * Test for exception if an invalid field name is entered.
      */
@@ -222,4 +251,22 @@ public function test_execute_course_id_string() {
         $this->assertEquals($this->course->fullname, $stepresults['course_fullname']);
         $this->assertEquals($context->id, $stepresults['course_contextid']);
     }
+
+    public function add_course_custom_course_field_data($fieldid, $courseid, $customfielddata) {
+        global $DB;
+
+        // Add data to the customfield_data table.
+        $data = new \stdClass();
+        $data->fieldid = $fieldid;
+        $data->instanceid = $courseid;
+        $data->value = $customfielddata;
+        $data->charvalue = $customfielddata;
+        $data->timecreated = time();
+        $data->timemodified = time();
+        $data->valueformat = 0;
+        $data->valuetrust = 0;
+        $data->contextid = \context_course::instance($courseid)->id;
+
+        return $DB->insert_record('customfield_data', $data);
+    }
 }