Remove the 4kTV
folder from your tv show library.
Peform a library scan,
then empty library trash.
Then let Plex compress its database.
Followed by “Clean Bundles”
(The latter two can be triggered under Settings - Server - Manage - Troubleshooting)
The above is basically a Plex Dance for the whole 4k folder branch at once.
If you named and organized your files inside the 4kTV folder strictly according to the rules for TV shows in Plex Naming and Organizing Your TV Show Files | Plex Support
you should be getting your shows correctly recognized when you add the 4kTV folder back to your library.
NB: don’t expect to get a separate poster for the 4K version, if you have a particular tv show both as regular resolution and as 4K version.