What can I do to troubleshoot this? Using TMDB for movies and TVDB for shows. It fetches all metadata / actors like normal, just not the images for the movie or show covers. I have cleared the caches from appdata>Local>caches and have tried rearranging the agents, with no luck.
Lets confirm the server version first, 4.22.1 is the web player version. Goto settings -> general (not plex web -> general) and you should see something like this …
Okay, so I’m on Linux and not Windows but I do see you mentioned you cleared appdata>Local>caches which looks different to what is suggested at this link …
… I would suggest first confirming this cache is deleted. Stop plex, delete/move everything in /Plug-in Support/Caches and then start plex again, give it a couple of minutes to start and then try and refresh metadata for a show/movie which was failing to download metadata.
If that fails could you paste a screenshot of your agents setup so we can review and also copy up the logs.