If you are an Adobe Creative Cloud user, it’s possible that the most recent CC update can prevent processes like online backups from working properly.
According to Backblaze [hat tip to Andy Baio], the CC update looks for the first hidden folder (based on alphabetical order) at the root of the Mac’s drive and removes the contents of that folder. For Backblaze users, a .bzvol hidden folder is created, and chances are it tops the list alphabetically.
Even if you are not a Backblaze customer, the CC update will delete the contents of the first hidden folder it finds alphabetically. That could cause issues with your Mac and its apps. If you think you have encountered this problem, you can try using a backup to restore the hidden folder.