OK, the clue is in here: guid="com.plexapp.agents.none://21953/17/9?lang=xn
agents.none means this episode is ‘unmatched’.
Can you verify that all other episodes of Family Guy are ‘unmatched’ as well?
This show has a lot of episodes, so Plex Danceing it may take longer than usual. But try it anyway.
P.S: if you come across any shows which use only 1-digit season and episode numbers, change them to 2-digit. This applies to the ‘season’ folder names as well.