We have a KMS licensing system running per core, so not with an actual license key but rather tied to the machine. With the last few machines, we always encountered an activation error, even though everything was functioning correctly. I should mention that the aforementioned logoff error also occurred with activated machines.
In this specific case, I've now addressed this problem and just found a solution... I was able to activate the machine using a generic AVMA key. Now, we'll wait until tomorrow and see what happens. I'll let you know as soon as I have any updates