I have set PFM to remove episodes from Play Later after they are done. This morning, I was trying to nice episodes around in the list and it was taking endless amounts of time. So I changed my settings to see all episodes, and all played episodes (normally I only show the ones that are downloaded) an lo and behold, my Play Later list contained hundreds of episodes.
Even weirder, while I was typing this message, without changing the settings, all of those hundreds of episodes disappeared. So it’s as if the Play Later database doesn’t update properly when “show downloaded only” is set to true, and “show played” is set to false.