Over the past year, on multiple Mac OS versions, on multiple Photoshop versions, on my old Intel MBP and on my new M1 MBP Photoshop has lost the ability to save files. A video is attached. (The MBP was up to date with all OS and Software updates at the time the video was made.)
When I got the new MBP I also did not migrate user data over, but instead set up everything from scratch, so this definitely isn't a preference file that was carried over in migration or anything; let alone that the troubleshooting with Adobe Phone Reps in the past led to me deleting all preferences on my Intel machine.
The problem went away for many months, but it resurfaced last week... it seems to be less frequent now.
The autosave seems to be uneffected, at least some of the times.
I just experienced the same problem. Eventually got my information saved by opening an older version of the same file, moved the layers from the new (unsaveable) version to the old version, was able to save that, and then had to abandon my new document. I also tried creating a new document and trying to move my layers there, but that didn't work. Now I have restarted and am updating the newest version of PS right now (I updated to the newest version—at the time—a few days ago.) I hope I don't have this issue any more! Scary. Could have lost a lot of work.