I will consider this as a feature for upcoming version if it seems to be an issue for multiple users.
Anyway the next version of mobile app will ask you to re-authenticate every time your launch the app if it was stopped for more than 1 minute in the next release.
Regarding Library items yes it’s due to the session timeouts. The live streams using the username / password authentication and the library items use the token (since it’s opened externally in VLC), this is why it behaves a bit differently.