I've been stumbling across this problem for a while now. It still requires login even if:
- I have supplied a refresh token
- Logged in via OAuth2 (as shown in the screenshot)
My clients: MUSIC, TV, TVHTML5_SIMPLY, WEB, WEBEMBEDDED
The plugin is running the latest commit snapshot (ab50625) and even in the latest release (1.17.0) it still has the same issue.