I, also am having the same issues. I can access all my one drive files I just can't open my vault. I've tried signing out and signing back in. doesn't help. Same two errors
- There was a problem unlocking your personal vault
- We encountered an unexpected error and could not unlock your personal vault.
I've also noticed that files on my onedrive are not being remembered for quick access. For example if I try to open the last used file in Excel or Word the apps don't remember and I have to physically find the file and double click to open. Not sure if that has anything to do with in ability to open the vault but both issues started at the same time.
Sure do hope Microsoft can fix this. Nort much value in having a Vault to store your most critical files & information if you can't access them.