If I understand correctly, when a Form submits changes, the automation is overwriting the existing file? If so, you may be hitting a scenario where the file contents have been cached. Maybe they are not being updated in a timely manner? Do you see the updated details after Syncing?
Just go in behavior then offline sync and turn “The app can start when offline” off and turn “Server caching” on and also turn “Delta sync” on. Now when you edit the data and save the new version of pdf the file is updated and you see the updated pdf when you click on open pdf file button. This worked for me let me if it works for you as well.
I assume you are overwriting with the SAME file name?
Google maintains file versions. I think that maybe AppSheet doesn’t handle this well. As if it gets the same file name and seeing it already has that file, discards the new version sent thinking its not needed.
If you have Server Caching ON, try turning it off to see if the problem resolves.
I have ALWAYS created a NEW file with a different name and therefore never run into this issue.