Since upgrading to the newest Plex plugin I can no longer use plugins for plex (installed to plexmediaserver/Library/Application Support/Plex Media Server/Plug-ins ). I am not sure of anything different I may have done
OMV is 2.2.5
root@openmediavault:~# dpkg -l | grep plex
ii openmediavault-plexmediaserver 1.0.15 all OpenMediaVault Plex Media Server plugin
ii plexmediaserver 1.0.0.2261-a17e99e-debian amd64 Plex Media Server for Linux