I have a 5 month old 45 lb male doberman puppy. His cage door left open and he is confined to the kitchen with a linoleum floor. He started pooping on the linoleum floor about a month ago at night time. His potty habits were good until then. He eats 1 1/2 cups of dry food 3 times a day with the last feeding at 6pm. He is taken outside often and I stay out there with him. I have closed his cage a couple of nights but he goes in there to. He started eating the bark mulch outside a month or two ago. He eats it like it is candy. It does affect how much waste he produces? I don't scold him cause I don't catch him I the act. He does see me clean it up though. I read that they should not see you clean up a potty mess. Why? He eats Canidae All Life Stage dry dog food.
Do I get rid of the mulch?
Cut him back to 2 feedings a day?
Close his cage at night and wait for potty habits to change?
Could he be missing something in his diet?
There were four separate piles of stool this morning on the floor. Unbelievable.

If he were mine I would cut him back down to two meals per day. When he went potty I would clean it up and toss it outside, hopefully he will get the hint that stool is to go outside. At 5 months I don't think it is uncommon for him to have a few accidents.
I would not let him eat the mulch. I have heard of certain type osf it being poisonious.