changes in grouped files fail to stick when ungrouped?

I hope someone can help me!

I have been witnessing a bug for a while, but had been convincing myself that I was imagining it. Now I can say with confidence that I’ve seen it happen twice, for sure. But I don’t know how to replicate it and I’m not technically savvy enough to prevent it happening or know anything about why it’s happening.

Sometimes when I make edits to files in group mode, the changes don’t stick, even though the indicator says the file is saved. The first time I was SURE it had happened, I thought it was an aberration, that maybe I had still imagined all the times it has previously happened, but now it has happened again, even despite my manually saving and backing up the .scriv (and every indicator suggested it WAS saved) literally right before I triggered the reversion of changes (by selecting an individual, ungrouped file.) Even the backup, when I open it, does not show the changes. I am so confused by why this is happening, and frustrated because I think I’ve been experiencing it for a while. Is anyone aware of this behavior? Do you know what causes it or how to fix it, and are all my edits lost forever?

My friend tried to replicate it on her machine, with her copy of Scrivener, and it didn’t fail to save for her. I have not yet tried to replicate it in other .scriv files, to see if it’s a matter of the file being corrupt or something else? Is there a place where I could go to find all my lost edits? I am feeling so distraught. I have lost days’ of work and not for the first time, and perhaps most alarmingly, I’m not sure how many times this has happened to me (but previous times when I thought I’d changed something only to find it changed back, I thought I must’ve been mistaken.) All my confidence in Scrivener is shaken, at the moment.

ETA: I can’t replicate it. Sometimes the changes stick. Sometimes not, even when the files says the changes are saved and the file’s backed up. Open the back-up and they changes are, in fact, actually not there. But when I try on purpose to replicate the problem, the changes DO stick. At least some of the time.