On import the normals are facing the wrong way. The mesh won’t even light up.
In Blender, the normals are facing the right way
I used bool tools to create this mesh. Could this be part of the problem? If so, how can I fix it?
I don’t understand the first picture. However, are you using a double sided mesh inside Blender with 0 Thickness, trying to get import that into Unreal and your inside doesn’t get light? If yes, did you try to check in the tickbox double sided in the unreal material settings? Would be great to hear if that’s what you want 
This could be a texture error if you are using a normal map maybe, i’ve had similar problems before, here’s how i fixed them if it wasnt the normal map!
This does depend on the geometry of your mesh a bit but has worked for me a few times when i got stuck…
Try exporting tangent spaces and/or loose edges depending on the mesh or just exporting normally and importing with the “Import Normals” or “Import normals and tangents” option… here are a couple of screenshots!
Export:
Import:
The double side material is a quick fix, but there’s still issues with the collision due the way the geometry is handled, such as I can walk through a wall where the normal is facing the wrong direction, but then once passed through, I am stuck.
Also sorry if this made no sense. It’s quite hard to explain.
Don’t use Complex Collision and make your own collision inside Unreal with simple boxes, and if it still doesn’t work, send a screenshot of your collision.