Problems after migrating to new server

[TheDreadPirate]

I've done a bunch of testing in my test instance.  Enabled NFOs (I don't use them normally) and it does indeed pull down all the season posters.

   

But only the actual season present is in Jellyfin.

   

At any point, even prior to your migration, did you have more content for the affected shows?  More than just season 1 for Seinfeld?  Or have you never had the seasons that are listed in all your shows?  Do you have the missing episode setting enabled?

What happens when you click on "..." for Seinfeld, Refresh Metadata, replace all metadata, replace all images?