even working out a script to get around the manually tricky steps.
Do you have this script in place on each of the layouts where you've tested this on your mac?
Might it be interfering with the expected behavior here?
Sounds like something may have been corrupted with Filemaker Pro for some unknown reason. One method that almost always corrected a problem on a Macintosh was to trash the preference files for almost any application. Well, not trash them but drag them to the desktop in case that isn't the problem. If removing them from the pref folder solved the problem, then delete them.
I haven't the foggiest where the pref files are on windows...but cmd click suggests Macintosh. Be sure to quit Filemaker before doing this. You will have to reset your Ram size and other stuff since it will all change back to default vales.
The clue lies in the statement that older files untouched don't work either so there has to be some conflict with Filemaker Pro.
Also since there has been a recent Mac system upgrade, did you upgrade to the latest and if so have you upgraded to 11.4 for Macs?
Many thanks for the help. I did all the above (trashed prefs, reinstalled, upgraded) and the functionality has returned. I did all three in one step, so can't say which was responsible for the improvement.