Here is a slightly different procedure for you to try:
- Go to your https://app.plex.tv/desktop#!/settings/online-media-sources account page and disable the Music/TIDAL provider
- On your https://plex.tv/users/other-services account page, unlink TIDAL, and then link it fresh
- Back on the Online Media Sources page, enable the Music/TIDAL provider again
- Wait 10 minutes for changes to propagate
- Restart (e.g. force-quit and launch) the player app