Good day!
While in a keep or tower that is owned by my faction, when I send my pet to attack an enemy faction from inside the structure, the pet indicates that there is no path to the target. I should also point out that there have been instances where this mechanic works intermittently - also, what may work in one location does not necessarily work in another.
Open field combat, or in the case that doors have been destroyed, the pet's operate and path normally.
My expectation is that while inside the keep or tower, I should be able to send my pet to attack a target outside the door. When attacking a keep or tower, my pets should have no path to a target inside - as my faction does not control door access.
