This has been bugging me for a while and I have finally tried to address it, so the server version may not be applicable.
Lats year I added some new TV shows. For some some reason (and I remember others having there same problem at the time), those shows got episode posters from other shows that I had in my library.
Wrong episodes were mixed up with right episodes and the wrong episodes all had posters from the same bunch of other shows.
I finally decided to do the full Plex dance for those effected shows but, when I re-introduced the shows to the library, I got the exact same episode posters back; shows that were right were still right and shows that were wrong were still wrong.
I tried the Plex dance again with the same result.
What can be going on here / what am I doing wrong?