Hello, that is no fun when a lot of work goes wrong. I think it might have to do with history. I would suggest trying to delete history before saving. I like to advocate for using incremental saves often using the Save Scene Options. There are other options that might help in that link.
Also, I suggest saving with .MA not .MB as the MA saves more information than an MB file. Or save as both. You might also try exporting to FBX before saving if you know it is going to mess up the UVs. The FBX might be able to save your work.
🙂