Plex Agent no longer working and Add to Watchlist option is also now gone

[Atomatth]

Sharing a relevant post from one of our mods.

@OttoKerner

Most of these issues are to do with an inability to contact plex.tv for metadata.
Check these:

• your server machine must resolve all plex related domain names successfully. This sometimes requires to use the public DNS servers of either Google 8.8.8.8 or Cloudflare 1.1.1.1 – as opposed to the default DNS servers of your ISP
• disable VPNs, then stop and restart Plex server to see if it makes a difference
• While Plex server is started, it already needs to have a working internet connection.
• Don’t plug in or unplug network cables, or switch on or off Wifi adapters after Plex server has been alredy started

A word of warning: switching metadata agents and scanners of a library around willy-nilly can leave this library in a non-working state.
So don’t do that.
If you want to test a different agent, create a copy of a small subset of your media in a separate folder. Then create a new library and point it to that new folder.

Also the codec directory does not have anything to do with matching, only playback.