Thank you for your post.
Unfortunately, I am unable to duplicate the problem. This is what I have done...
I created a test database file (Test.fp7) with two tables: first and second
I created an ID field in both tables and set the relationship based upon this field.
I created a pop-up field that uses two related fields, but only displays the second field.
I added 50 records and several values to the pop-up field.
Scrolling up and down in Table View does not appear to change any pop-up value.
Just in case I'm missing something, it may be better if you send in your database file. I will try to duplicate the problem here and determine if it is a FileMaker problem or a damaged database. I have sent you a private message (top of this page - right side - X Messages) with instructions where to send the file.
I have received your file, and I'm able to duplicate the problem. As it turns out, this problem was previously reported, and I have attached this thread along with your file to the original case. When more information becomes available, I will let you know. There is no workaround at this time except to switch to another layout and then back again.