Project crashes when copy+pasting, and the autosave files aren't compatible

I copied a 12/8 riff over from a violin part to a chime part in a different segment of the piece. The entire program window just up and popped out of existence. I looked in my recycle bin for autosave files, and I found one, but it was saved as .autosave and couldn't be read by MuseScore.
I don't have a file, because, you know, it disappeared. I'm not sure how reproducible it is, but it happened to me twice within three minutes, since I opened the restoration and tried to do it again. The next restoration gave me a version of the file from a week ago.