I'm sorry....I know it can be very frustrating ! You may have to go all the way back to the beginning and start at square one again. Does he go outside or on potty pads ? If you take him outside , you may have to go back to the puppy schedule. Taking him out every two hours or so , and if your not home confining him to a play yard.
What I did for my other dog ( our Yorkie uses pee pads inside while Sydney goes outside, she's bigger ) was use potty pad inside and outside so she knew what to do when I took her outside and where to go if she couldn't make it outside. She knew when I took her to the pad what it was for.
Then we gradually made the inside pad smaller until she only has the one outside (that she could see ) and she knew she was suppose to use it so she would let us know she wanted out and she would use it ( and we still kept taking her out regardless every 3 hours or so) ...then we started making that one smaller too , until she just using potty outside with no pads. It took a good 6 months or so to get her to that point that I would say she was reliable to not have accidents and really knew what she was to do.
I also suggest keeping treats on you at all times. I used a little nylon travel bowl w/ strap to keep them with me so I Could give her one every time right away...that worked wonders for me. She loves her some treats !!!!
It gets annoying so I just strapped them thru a belt loop.
My Yorkie is only 8 mo. old and she is my first one so I have no idea about the Yorkie " never fully getting it" part. Chloe did very well , so I think they can get it , they may just be more stubborn about "when " they choose to use their knowledge
