Last tested: Oct 2, 2020
There's been some instances where users click "Stay Logged In" but they'll still receive the 30 minute login notification as if persistent sessions was disabled. Try asking the users to log out, reset/clear their browser cookies, and logging back in while checking Stay Logged In.
Once they're in, have them navigate to:
And check to see if their new session that was created will expire in a month. If so, have their users log out, clear cookies, and log back in!