EDIT: I also crossposted this to the Geodatabase subforum as I found it after making this post and that seemed like a better place for it. Moderators, feel free to delete one of these, if needed.
This is a bit of a Hail Mary, but:
Last week, I was working on a project in ArcGIS Pro 3.1.0 that used a File Geodatabase that was stored on a networked server (not AGOL) in my organization. Throughout the week, I periodically copied that entire FGDB to my local machine as incremental backups.
Then on Friday right at the end of the day, I was testing some Python scripts and made yet another copy of the FGDB, just in case. Sure enough, I had to roll back to the backup after the testing, so I deleted the FGDB on the server and pasted in my backup created just before the testing, then reopened ArcPro.
Suddenly, all of the work I did last week is gone. It's like that backup was from before I started the project on Monday.
I checked all of my other incremental backups, and it's the same thing.
Things I have checked:
Methods of copy/backup used:
(I use each of these more or less interchangeably, and feel confident there's at least one example of each among my incremental backups):
I even ended up with backups in more than one location on my local drive, and all of those backups are showing the same behavior.