How big was the dog. Some big breeds with fluffy hair need a LOT more room. I had one dog that kept going into an area and just standing. The other big dog, not fluffy, the Sims, the cat, no one else had trouble using the door.
When I cancelled the action, or teleported the dog, he'd do something else and then go back. Finally I ripped down the wall and that allowed the dog to get through and he stopped wanted to go up there. Then I rebuilt the wall and put plants to keep everyone out.
I found often if a "Sim" gets a new path in their "head," so to speak, they will always take it. Use the traffic cones to block it and they will find another way and given time use that way, even if you remove the cones.