Can't force beginSession to use vr::Api::API_OPENVR on the Rift

[simongeilfus]

Trying to force the context to use OpenVR with the Rift throw an exception:

mVrContext = ci::vr::beginSession( 
    ci::vr::SessionOptions()
        .setTrackingOrigin( ci::vr::TRACKING_ORIGIN_SEATED )
        .setControllersScanInterval( 0.25f ), 
                ci::vr::Api::API_OPENVR
);

12/07 14:34:39.853 {INFO}    [Kernel:Default] [CAPI] LibOVR module is located at C:\Program Files\Oculus\Support\oculus-runtime\LibOVRRT32_1.dll
12/07 14:34:39.862 {DEBUG}   [Client] Connected to the server running version (prod = 1).1.5.0(build = 241049) feature version = 0. Client runs version (prod = 1).1.5.0(build = 241049) feature version = 0
|error  | VrTeleportationApp::initializeVr[90] Session failed: Device manager not found for deviceVendorId=2