Per quite a few reports, some of the make your own treats are now excluded from the snack credits. It seems to vary day by day, CM by CM. Your best bet is to ask when you get there which items the snack credits can be used on.
I'm disappointed in this as most reports have said that the MYO Mickey Rice Krispy Treat is now excluded. Some have stated being able to get it but only with the coating, none of the toppings. I was so looking forward to one dipped in dark chocolate, topped with pecans, and drizzled w/caramel.