Originally Posted by Snacky

I just found out that I had to "always allow" third-party cookies in Firefox, to be able to stay logged in to the A3 M+B website and access my account details. It's not enough to only check the "allow cookies" checkbox. When I use IE11, I just use it in a standard configuration, so I guess that's why it just works (and at the same time allowing any and all nasty tracking devices to have at me, tearing my privacy to pieces).