Found it.
You installed the SNAP package from the Ubuntu App Store. They changed the App store. It only dispenses SNAP apps now.
SNAP packages can only use software and are confined to your home directory. (They are locked containers)
Jan 27, 2021 01:02:47.449 [0x7f10a000e700] INFO - Plex Media Server v1.21.2.3939-3945797bd - Ubuntu snap x86_64 - build: linux-x86_64 snap - GMT 02:00
Uninstall it
Download Plex from https://plex.tv/downloads (x86_64 version)
sudo dpkg -i filename.deb
Now setup again and enjoy 
