This was a recent change.
Plex is pushing the Plex HTPC app as remotely controllable target.
From Plex for Mac, Windows, and Linux - #63 by Moussa
Version 1.46.1 has been released for Plex for Windows, Plex for Mac, and Plex for Linux.
NEW:
- Remove support for being controlled as a companion player. Use Plex for HTPC for remote control playback on the desktop.
According to the shortcuts listed in the app this is still working (using f or \). At least that’s still working for the Plex desktop app on macOS. I think F11 is using a native functionality of the operating system (Windows) – I don’t think Plex has any influence on that.
