Yokies can jump like a cat! I also had the same trouble.
At 16wks Buddy jumped over the baby gate I put up across the kitchen.
I would put bar stools in front of the gate so he could not jump and he
somehow still got on the other side. I went out and bought another gate
and stacked them one on the other. Problem solved!
It looked like a pit bull was blocked behind those double gates.
Carol & Buddy