Hello,
When using movement enhancing abilities the pet gets easily left behind since in combat it moves very slowly. The pet is a core part of the Unholy DK spec and this cripples UH DK’s allot in these scenarios.
I suggest making the pet inherit the movement speed of the player to fix this problem.
This problem is easily seen in Legion Remix where you have such high amounts of movement speed that the pet gets left behind and despawns and can not keep up in combat.