I am also having the same issue here, never had a problem before! I also use PLEX. I have 4 drives all stored on different accounts, and a 5th I use for direct backup without CloudDrive. I am basically at a total loos on what to do! I am using version 18.104.22.1688.
I would appreciate any help that is available!
I run my PLEX on a dedicated server in a datacenter, amazing bandwidth, hence using 5 accounts to alleviate the daily upload cap.
Could this be something with the changes from GSuite to Workspaces?