Plex Media Server v1.41.1.9057 (current beta)
Voice activity analysis is apparently not working as a scheduled task right now (no info on when it will be fixed).
It is working when new media is added if so configured in Settings → Library.
You can also start the process manually by analyzing a movie or tv show (show/season/episode).
Choosing analyze for an entire library does not work (three dots → manage library → analyze).
However, you can select multiple movies or shows in a library and then choose to analyze them.
