Major Files randomly delete themselves

For the past few months now, I've been working on a Major Waltz, one very similar to the Mephisto both in theme and difficulty. The Cynic Waltz was about someone I consider quite Cynical, but someone I very dearly none the less. It was a 16 minute long piece 454 Measures, and I had put nearly 160 hours into it.
But early on in the development something happened, the file was auto-recovered this scarred me cause I've found that in the past Auto-recovered Musescore files get deleted after a PC or Musescore is shut down.
So for weeks I avoided my PC getting shut down, all to keep the Cynic Waltz from getting deleted, today I began to think I was wrong in paranoia about the music so I closed the 15 music tabs I had open on Musescore including the Cynic Waltz keep in mind I have saved The Cynic Waltz thousands of times by this point.
When I came back to listen to the Waltz, it was gone. Everything I wrote in that piece was gone, there's no autorecovered version as I believe the fact that it was recovered once means that it will be deleted.
But for some strange awful reason the only piece hit by this glitch was the Cynic Waltz the only truly emotional piece I've written, and what I would consider a great piece of music...
Most importantly I don't care that my piece was lost, that much, what I do care about is the fact that such a glitch exists in a program meant for composition. How is one supposed to Compose anything when it could always just get deleted?
(To add, I made many copies of the Cynic Waltz, but none of them ever saved, because for some reason Musescore almost never makes a copy no matter how many times you try)