Server Version#: 1.15.4.993 (and at least last 3 versions)
Player Version#: Many
I believe this is probably quite widespread but goes unnoticed.
Plex Dashboard and logs (even in verbose mode) occasionally does not capture media being streamed. See more info here:
https://forums.plex.tv/t/now-playing-and-plex-logs-not-capturing-all-activity/354110
I built a separate server on Debian (original was Windows) and error still occurs.
Update: Dashboard Bandwidth does show activity but doesn’t show what is playing when this happens.