I don't know that I've fixed the issue yet. For now, I back up every time I exit. Once I made the changes below, I've only had to restore a backup once. But now, when adding fixed assets, the asset number is duplicated and can't be changed.
Months ago I was told by QB support that the program is confused if I backup anywhere except my hard drive. I had backed up to an external Seagate.
I have excluded the FAM directory from both my virus protection and my OneDrive.
Today I have talked with support and shared this thread that started December 19, 2019. Support said that he took a screenshot to send when my file is escalated (for another issue, recurring asset number assignments!)
Good luck. I hope there is a fix soon.