How exactly is this form usually used?
Does it automatically show data when it is launched? Or do you have to search for it?
If it auto-populates, then it might be using a setting in under Tools -> Options (on the menu bar)
If it is set to “No Action” then the loading of data/filtering is being done in code at the form level.
If I inherited this, I’d make a BAQ for UD09 just to see what is being stored in it. Maybe a BPM adds the records, and another BPM deletes them. Or maybe records only ever get added, and the form does the filtering of which to show.
EDIT: If the BAQ for UD09 shows no records, then that would be why your “tracker” is blank when it’s launched