Mine was last night. Check in did not become available until midnight on the dot. Had to complete check in before the link to book activities appeared, but it was dead. Seemed to be a system issue - neither the app nor multiple browsers would work, and all my activities that I had already booked for an earlier reservation also were not available to view. Maybe system maintenance last night? In any case, I was able to book everything I wanted this morning, but I’m still irritated that I stayed up until midnight and then couldn’t book anything.