Not sure the best spot to put this since it’s not client specific and I’m not sure it’s server related at this point.
I’ve got a show that if it is marked as unplayed always wants to start at Season 05 Episode 01. Even if I start watching S01E01 manually, the next time I come back it wants to start at S05E01 again. I’ve done the plex dance by removing the entire show, and the issue persists.
Double check the date metadata for the S05E01 and S01E01. Maybe S05E01 for some reason has an incorrect “Originally Available” date, which will play first. Plex’s “Continue watching” should choose the earliest - chronologically - file of all files in all seasons to put up first. Try refreshing the show’s metadata to see if it gets normal-looking dates. If S05E01 has a date for some reason earlier than all other episodes, and that is the ONLY episode that is messed up, try changing it’s “Originally Available” date manually.