I would like to confirm when the datatransform "OpenDefaults" is called.
Is the datatransform "OpenDefaults" only called in in situations where the user is calling UI? Thus, opening objects via activities, flows, (dx-)api calls, queues processors and such do not trigger "OpenDefaults".
@BobReawaruw I found the below explanation from another user question:
"When you open a work object via the "Find by ID", or "Recent Work item" you are opening the work item itself.
However, when you click on a users work list you are opening the assignment and not the actual work object.
The user work list is really a list of assignments and not work objects, so when clicked the actual assignment is opened (of which there could be several on a single work object for different users) rather than the top level work object.
This is intended behaviour as the additional call made to OpenDefaults when opening a workobject will not necessarily be applicable to an assignment.
For this reason there is a separate extension point activity for assignments called Work- PerformDefaults when opening an assignment from a worklist."
It might help if you could explain what is the issue you are encountering.
Perhaps you can run a trace to identify if the reason that your OpenDefaults rule isn't getting called is that Assign-.ProcessAssignment doesn't call any activity that references OpenDefaults.