i’m guessing that I have this going on: remote sync (it would be very helpful if plex would identify syncing as an activity and show it. Can not understand why plex doesn’t (not knowing what is happening causes at least to different problems: 1) has your server been hacked? 2) is plex doing something it shouldn’t) at least that is what was running through my head.
I found this post which help me investigate the logs:
sure enough it appears that it was a remote sync, of which there is no good way of monitoring short of looking in the logs