We have pretty much given up on getting our Higgins poop-trained. Welcome to the club.
He's not so bad about the peeing, but he just poops on the run anywhere. Like you, we praise him to the skies when he does it outside, but we just give up on the inside poops. Mostly he just goes before we get up in the morning so we only have to go on poop patrol once a day. And fortunately, they are nice dry poops that don't stick to anything and don't have much smell to 'em either. We think he knows perfectly well what he's doing and is just being a defiant little stinker......but he's soooooo cute.......good thing, too!