The requiredBandwidth is calculated during Deep Analysis, which runs during the server maintenance window.
In Settings -> Server -> Scheduled Tasks, check the box for Perform extensive media analysis during maintenance. I’m not sure how long all the scheduled tasks take. It will depend on the size of your libraries. Suggest you pick a wide window for the start/stop times, at least to begin with (I run Plex on a NAS, which is on 7x24. I’ve never tried to time how long maintenance tasks take).
See Plex Docs -> Server Settings -> Scheduled Tasks for additional information.
If the analysis does not run during your maintenance window, you can Plex Dance the movie. This removes all traces of the movie from your system, so Plex considers it a new movie when you add it back. It will then analyze the movie just like it would for any other new addition to your system. FYI, you will lose played/unplayed status, play counts, etc if you do this.
You can also run the scanner via the command line. Use the --analyze-deeply action. See Plex Media Scanner via Command Line.
