danielunited could possibly be browser-related, which browser are you using on desktop and on mobile? (please provide OS too if possible)
Have you tried using a different browser? Clearing your Flarum cache will not clear out any active sessions which are stored under storage > sessions in your Flarum installation directory. This goes the same for your browser cookies as well, unless you explicitly specify to do so when clearing cache and other site data.
You can see from my example below that if you don't click on "Remember Me" when you log in, your active session expires the same day. Clicking on "Remember Me" will store a cookie that keeps your session active for 60 months from the day and time you ticked that box.
Flarum checksfor the same session token that's stored in storage > sessions against your browser cookies for your site to verify that it is indeed you and to keep your active session for the day or for the entirity of flarum_remember.
Other than that, can you provide the output of php flarum info ran from the root of your Flarum install?
