Sometimes it’s just easier to wait in adding episodes and just add the entire season in one big dump, unless you want to do the tired old Plex dance every week.
To get the metadata into the file, I use MetaX, it fills everything, titles, descriptions, airdates, directors, actors, producers, writers, season number, episode number, tv network etc., this way the file is universal if I want to move away from Plex. And theoretically Plex should add nothing I don’t already have, but for some reason the new TV agent doesn’t respect the local assets and local metadata options even when checked, it’s pretty much my single point of frustration with the TV side.