No Records Shown on Linked Subform

I have a strange one here that I'm hoping someone may be able to help me with.
..

I have a form that shows data from a record who's primary key is the
"Report_id". On this form, there is a tab control. On the third and final
tab there is a subform to show child records in another table. The
master/child fields are set properly, and there are no filters in place.

When I add a record, everything works perfectly. The data is saved, and the
report_id is taken from the parent record. If I close the form, however, and
then reopen it no records show up. The data is there in the database, and
the data is correct for the linking fields, but they just won't show up on
the subform. I can add more records to the child table through it, and again
they will be saved appropriately, but after closing and reopening the form
they, too, do not show up.

Anyone have any clue here? I'm down to the last chunk of hair on my head

Ok, so after trying everything I could think of and examining every property
10 times, I decided I would remove the subform, and then re-add it.

It works.

All of the properties are the same, no code changes were made, but it works.