NavMesh problem

I have 18 nav mesh bounds volumes on one level because map is very huge, some of them are overlapping and my enemies are not moving around nor patroling, even those ones where navmesh is not overlapping with another. Any ideas how to fix this ? Using 1 nav mesh on the whole map consumes more then 300.000 points and last time i tried buiilding 1 nav mesh with 300.000 points an error pop out that says i overexented my limit with 1 nav mesh (not those words exactly, but you get the point) . But with those 18 nav mesh volumes it take only 60-71k points.

Believe it or not, i had to use collision on all the meshes around the world to “use complex as simple” so navmesh could start working, ue4 is really weird sometimes…