Nothing is more fun that finding out a production server has not been activating via KMS like it was supposed to be doing. Imagine my surprise logging in and seeing a “Windows is not activated” message. Re-entering the correct kms setup didn’t solve it; in fact, it didn’t even send a KMS message to the server.
It turns out the server was in MAK licensing mode. I found that out by running the command “slmgr /dlv” in an elevated command prompt and seeing VOLUME_MAK in the description.