Bug found - Mob disappears and reappears over and over

Link to Twitch clip showing the bug I encountered.

I was in Ebony Barracks near the waypoint with the stairs. When the mob comes off the stairs it disappears. I approach the stairs and it comes back out of thin air and disappears again.

https://clips.twitch.tv/ThoughtfulVibrantOwlSmoocherZ-4tp3Hz0udGgFW5F7