Been having some issues with the Dogs and Cats Mod Addon.
Firstly, when having the dogs sit, they seem to sit and stand just fine. However, logging off the world then back on causes dogs to just stay still, even when standing. They will no longer follow, teleport to you or move (other than wagging tails and turning to face you). There is another issue that I assume is related to this which caused the dogs to sit on an angle (legs angled to the left) then when having them stand, they will follow you- but will be half way in the ground and body will be contorted into a sideways U shape???
The final issue I have is that pet merchants don't seem to be spawning. I have the mod "Village Names" installed which gives villagers new textures and looks, so that might be conflicting with it (but is unlikely since the Fossils and Archeology Mod's archeologist still shows up).

I wish I had pictures or video regarding the first two issues I have, but I ended up "putting them down" and haven't found any other dogs (foxes and wolves) since.

edit: apparently I don't even have to log out of the world for the dogs to stand still. If i just have them sit and then stand- not logging out- the still remain still (not moving or following)

I am having all of the above stated issues with my wolves (once tamed) do not follow, only sit or stand. If you try to pull them on a lead they move for a moment then sit down. I've never seen a pet merchant spawn anywhere despite finding many villages.