Large sections of Nav Mesh getting wiped by dynamic obstacles.

This is an image of two identical turrets. The both have collision spheres set to be dynamic obstacles (the red circle around the base) but the one on the left wipes a large portion of the nav mesh as well.

And here we can see what happens when I move it slightly. The area wiped grows. It should be noted the orientation of the clear area aligns with the nav volume.

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So what should have been a way for Pawns to navigate around an obstacle turned into a trap they can never escape!

Anyone have a clue as to what is going on here?