pit lord, from the talent Gul’dans ambitions is broken right now. Instead of attacking the target of the warock, he attacks the closest target from the agro list (all targets that has been in combat with warlock at the moment of summoning Pitlord). You cannot retarget him, even with the follow-attack commands.
I has reported this issue numerous times on PTR on the forums and in game bug report tool, and still - here we are, a month since it was reported and still it isn’t fixed.