I am not sure if it's a bug, but it's curious that only xenforo.com seems to be affected by the issue I am experiencing. I cleaned my Chrome cache in every way possible, multiple times. Every site I need to log on to remembers my login details and logs me in automatically every time. Only on xenforo.com it doens't work anymore (I have this issue since a couple of days).
In Firefox there is no problem however.