I find that when submitting details while logged in to my BAEC account, it will always fail. Try entering MMB while not logged in and try again.

The problem I have is that wherever I fly to, I always get the "we must first check your passport and visa" message on boarding passes. Even on flights to the UK and I have a UK passport. On flights from the UK to anywhere in Europe I always get asked to show a visa. Most agents roll their eyes, say something along the lines of "visa? for a UK citizen?" but other less experienced agents are sometimes more difficult resulting in supervisors needing to be called. Curiously, this has started happening from the time I entered my US Known-Traveller-Nuber for Global Entry. Couldn't be a bug related to that, could it?