Hi and glad you joined us here in Yorkie Talk.
The only suggestions I have for Maximus is maybe to start "crate training" him. Also, he is probably smelling "old" urine spots on the floor(s) and because of doing so is returning to the areas to relieve himself.
There have many posts on the "housebreaking" dilema's and sometimes even the older Yorkies who used to be so trustworthy on going potty where they should had to revert back to "basics" on housebreaking.
And the "treat" reward for pottying in the right spot is excellent, keep it up.
Wish you the best with Maximus and send pics of him when you can, we adore pictures around here.
