I've never had a dog like this before, but this is also our first small dog. Nikko basically refuses to pee or poo infront of us. He will hold it for hours, only to make a huge puddle and poo as soon as we leave him. It is making potty training even more difficult than normal! He's using his pee pad and going outside about 50% of the time . . . The other half he'll go on the floor in the hallway a few feet from his pee pad

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Is there any obvious solution to this that we're missing? He's so unwilling to go infront of us that he'll even hold it until he gets in his play pen for the night and then go in there. Last night we put him in and came back downstairs 5 minutes later to find that he had peed and pooped in there in that short amount of time! He also has a small crate (which he hates) and he'll "go potty" in there too when left for a few hours. . . Yet he'll hold it for long periods if we're with him for extended periods of time (if he's not out of our sight at all).
Also, just to clairify, he has has this problem with refusing to go infront of us from day 1 when we brought him home from the breeder. She used pee pads in her house and I have no idea where this issue with not going infront of people came from. One the (rare) occastion that we do actually see him going, on his pee pad or outside, we praise him like crazy and give him treats.