how old are they? Most gliders grow out of this. But, some will do it always. They do get better at the grooming as they age as well. They will potty just after waking up, so you might make sure if you are waking them during the day to let them out of the pouch right away.
Val B
Mom to
1 human son
21 personal gliders + rescues looking for forever homes
6 birds
4 dogs
If they can't get out of the pouch for potty breaks, YES, they will go in their pouch. You need to give them some privacy and then they will learn to do their business somewhere other than in their bed.