You should be able to add an exclusion for Plex media server into malware bites. Check in the app settings and exclude the main Plex executable process and maybe some of the other processes related to Plex. Actually I think the portion of the log that you posted includes which process was affected so just make an exclusion for that process. All of the executables for Plex media server are in c:\program files (x86)\Plex\Plex Media Server, just choose the executable that was listed in the log. Screenshot of executables:
Yep, that’s it, they say to exclude all of the executables. I think with Malware Bites, you can choose the whole Plex folder, so just exclude the folder itself. I removed MWB a log time ago because of this.