Why Is Nav Mesh Volume Messed Up In My Scene?

So I’m trying to put a nav mesh volume in my level to allow A.I characters move around the environment but I’m getting these very stupid abnormalities where the nav mesh breaks with no rhyme or reason. In the first two screenshots the nav mesh gets lifted into the air even though there is no visible (or invisible) collision. I can walk through the space but A.I can’t pass through (obviously). I can delete all the mesh in the area and put a flat plane and still get the same issue. I’ve tried adjusting the agent radius, adjusting the position of the nav mesh but nothing is changing. I deleted every conceivable mesh, brush (invisible) possible but still getting this. Is there any way for me to see if there is anything blocking its path? or how to adjust the accuracy of the volume besides the agent radius?

Another example of a nav mesh over a flat surface. What is with this shape in the middle? ITS A FLAT SURFACE. It makes zero sense.

So in the project settings I checked off “Draw Path Colliding Geometry” and I suspect these invisible white shapes are causing the collision issues. I remember what they were because I deleted them a while back but for some reason UE4 is retaining their memory and I don’t know how to get rid of something I literally already got rid of?