Cannot Delete Attribute

[BloodyIron]

When I try to Delete a Multiple Express Entry Attribute I get:

An exception occurred while executing 'DELETE FROM AttributeKeys WHERE akID = ?' with params [99]: SQLSTATE[23000]: Integrity constraint violation: 1451 Cannot delete or update a parent row: a foreign key constraint fails (concrete5.atExpressSelectedEntries, CONSTRAINT FK_C9D404BBA2A82A5D FOREIGN KEY (avID) REFERENCES atExpress (avID))

And I really see no way to fix this for myself so far... :/ this is seriously breaking

[BloodyIron]

This issue still exists for me, fortunately only on dev, but still I don't know what to do about this. Any advice @hissy ?