Can't log in on Firefox for Android

I just had some struggles logging into my account. I got in on Firefox Desktop and Jerboa after a password reset, but I still can't log in on Firefox for Android. When I try to log in, it says "logged in" in a small popup, but it's not logged in.

It's not that big of a problem for me, but I can imagine if someone has that problem without using an app it could get annoying.

Edit: It's a problem of moderate size for me now.