You’re gonna want to check my post in this thread, or at least this thread in general:
Long story short, the .bz2 update packs that are distributed by Plex have some files moved into a folder (vs where they used to be) and if you move them manually back to where they are supposed to live, AND restart your Plex/server, it should be back to normal.
I can’t speak to that PMS updater script because I copy update files over manually via ssh, but my fix may work for you and couldn’t cause any harm to try.