We’ll see.
Instead of specifying a directory for it to refresh, try specifying the show’s item ID. You can find the Id by doing something similar to the following:
Plex Media Scanner --list --section XX
This will list all the shows and their item IDs in that section. You could then do something like:
Plex Media Scanner --refresh --section XX --item YY
This should cause the metadata for the specific show to be refreshed. You can try adding --scan and --analyze in there too, but I don’t think they should be necessary.