Yes, at the time of your post, I temporally disabled ATK's backend for a few hours because of memory constrains. It should have come back online during the following night.
Indeed I, too, would appreciate an UI tooltip for the case, but it seems most Firefox addons suffer the same problem of low maintenance due to what I personally name "low users' interest" and also due to clashes with AMO review practices.
Edit: BTW, for your information, every time ATK should stop working, it'd be because the backend becomes unreachable. The user's client is always expected to function properly. However, the backend uptime is generally pretty high so disservices should be rare from what I can see in logs.