I suspect the 'issue' is in Plex itself. I believe the 'previous menu' command when viewing video launches the on-screen menu rather than backing out of the playback into the previous menu.

For whatever reason this worked previously, so the behaviour may have changed in a recent Plex release. I've not modified any keymaps, but I will try deleting and letting Plex rebuild to see if that helps.

Failing that, a workaround seems to be programming a key press/hold as the 'Stop' command. I preferred the old method though and will try to find a way to get it back.

Will post once I work it out.

Regards,

Tom