User hook not working in HR forms application

I have created a user hook package procedure to provide additional validation on the assignment grade. The hook code is called from the PER_ALL_ASSIGNMENTS_F after insert and after update row handler procedures. This works correctly when updating an assignment grade via templates, but does not appear to be called when using the forms application. I have also tried calling the validation code from the UPDATE_EMP_ASG_CRITERIA after process hook. We are currently on forms application 11.5.10.2.

My first question is, does the forms application actually call either of these API modules when an assignment is created or updated?