I did mobile orders both in the morning hours and early afternoon and the pop up showed up both times so I assumed it was a permanent thing. Contempo never had a line either time I went, so it's not really needed IMO.
When I last saw it, it was around 10:20PM. The MK closed at 10PM, the app was showing a pick-up time window of 10:35PM-10:40PM and the cafe was closing at 11PM. But there were only a few people dining; we placed our order with the cashier (we weren’t guests) and the food was out within a few minutes.
The algorithm the app uses to calculate waiting times is frequently wrong — I’ve seen 45-minute waits projected but had my food in 5 — but it’s probably still set to “protect” guests. That is, in my case, give people in their rooms time to order their food before it closed.