Motion Blur (Artifact?) Visible Through Walls

I’m having a weird artifact from motion blur and not sure why it’s happening. During a scene, I have a spawned character run past a window for a jump scare kinda thing. But when the character spawns and through out the animation, the motion blur appears inside the walls of the building and on top of other characters.

I’ve uploaded the frame close up and a selection of the character of the frame so it’s clearer that the character is indeed behind the wall.

What could be causing this?

Things I’ve tried:

Turning on and off motion blur in post processing. It’s still there.
Turning on and off Temporal AA
Turning off Per Bone Motion Blur on the actor fixes the problem but not a good solution as it basically eliminates all blur.