I noticed last year during MNSSHP that only a couple of CS places were open. Cosmic Ray's in Tomorrowland and (I think) Pecos Bill in Frontierland. This could be happening later in the evening. I didn't notice until after 9 pm.
Guessing Main St. Bakery stays open, but may run out of sandwiches and just have treats.
There are plenty of snacks there to use your credits on, but I would rather spend snack credits on F&W plates at Epcot. That saves a ton of money.