Stubborn Rhodesian Ridgeback mix refuses to poo outside?!

Our 11 month old boy has been refusing to poo outside and I just can’t figure out why! We have no problems with him peeing inside, but when I comes to poo?! Geez, I just don’t get it! We will go outside many times a day, 15 minutes at a time and he will still come inside and poo in the basement. Any tips or ideas?

Jeff’s crate is in the basement, which sounds bad, but it’s essentially our day time living quarters! (Office, game room, storage, hangout spot) so, I’m not sure why this is his go to potty spot!
He’s Rhodesian Ridgeback mixed with Staffordshire Terrier, so he’s absolutely stubborn and I’m just trying to get some idea as to why he won’t poo outside. We keep the yard clean, the grass is always cut...it’s a safe place, but he’s just being a butthead about it. >.<