I had this issue till a few minutes ago, error didn't start until earlier today, but I been having with unclean shutdowns for the last two weeks. Game back from a 3 week vacation and have been trying to resolve that when the Plex container stop working. Did a remove and reinstall, but would not work, log showed this message " "Critical: libusb_init failed"". Deleted all but the Plex-media-server" folder and reinstalled, but still no go. Then I say someone change the Key4 from Latest to plexpass applied this than change back to Latest and applied.
This fix the problem with Plex not opening and I was able to recreate my libraries. Earlier today I removed my nvme cache drives for a sata drive and the Plex container didn't like it, now I have to wait to see if my reboots stop happening on my Unraid server.