A Microsoft file hosting and synchronization service.
Hello
Can you still access your Vault? If so, move the files in the Vault out of there first, and move them to a different folder.
Then delete the Vault icon.
Refresh the folder, or reopen the folder after that. The Vault icon should be recreated, and it should hopefully clear that error message. You can then move the files back into that folder.
I am hoping that should also go to fix the other files' syncing issue, as the Vault.lnk issue might bottleneck it.