App not saved, suddenly I was working on an earlier version of the app

I was working on my app and suddenly it started behaving strange, in the preview it was showing items which I have already deleted.
I went to the home page and when I got back in the app, it was an earlier version, around 1 hour before… this means I lost 1 hour of work + need to find at which point this was saved.
This was around 00.20 CET.
This is the project:

I’ve been noticing this too sometimes. Though not that much time.