Assuming that this is the typical relationship controlled conditional value list, what you describe should work the same in either version and the versions in between.
Can you show the Manage Value lists dialog that shows what options were selected for the models value list?
Did you just convert the file and find this problem or did you make some design changes? (or try to recreate the original design in a new file?)
Hmm ... I think I've figured out my problem. But . . . for SO many years, FMP let me DO this without complaining. Now, since FMP12 file format, you can no longer do this 'wrong' (I assume) thing.
Here's what I believe I've done 'wrong'.
In FM7 (file format) you could leave the "Include only related values starting from" option BLANK ... or "<unknown>". Simply leave it, and it would pull from the same table. See screenshot.
But, if you do this in FMP12, well, it "won't work". And that's not SO bad if you do it anew ... and then poke around to see what you've done wrong and do it RIGHT.
However, if - like me - you've been doing this for 10+ years and simply convert the file from FM7 to FMP12 ... the results are poor. It ALMOST works for you, but, then you run into the same problem I've described above - that is: the Relation will work ONCE ... but if you change the "Make", then the "Model" won't update.
And so . . . whether or not I understand IF what I was doing in the past was actually 'wrong' or not (well, come on ... it WORKED ... one assumes it's 'ok'), HERE is what I need to do now in FMP12 (again - any version of FMP12+ will behave the same) to get this to work:
SOLUTION: you MUST choose an option in the "Include only related values starting from" list ... and, it thus cannot be left BLANK (although, you're not forced to choose anything ... which isn't all-that helpful).