Unity Player Accounts and Soft Logins

Hello,
we just switched to Unity Player Accounts. We show a login button to sign the player into the service

cache the access token and reuse it to do silent logins

AuthenticationService.Instance.SignInWithUnityAsync(acesstoken);

but after a while these access tokens timeout and the user has to go through the signing process again.
What am I doing wrong?

Please check this thread with the same issue: Unity Player Accounts Login Every Time