Issue with last update of Plex Media Server Version 1.18.3.2156 in order to cast to Sonos

[darcilicious]

I think it is on the Plex side and probably has more to do with an update for Sonos that was recently announced:

Plex for Sonos

This release targets Sonos Companion from Android, iOS, and Web specifically: NEW: Use any authenticated Plex device to control your Sonos queue via our casting integration. Android, iOS, and Plex Web will now see and control a single queue per speaker. Start playback on web, pick up your phone, and control while you move about your home using the familiar Plex app you know and love FIXED: Playback on Web and iOS could sometimes cause the UI to stop updating the timeline scrubber and playb…