Static Navmesh not working in Sub-levels?

Hi Guys,

I’m looking for days some kind of solution for static navmesh problem
Since version 4.5 and last 4.8.2 version i’ve the same problem

When I play one Level (without level stream calling script)(Opening Graveyard.umap and Press Play) navmesh works perfect, but when I load the same level in a sub-level mode (Persistent Level “Loader.umap” calling LoadStreamLevel function for “Graveyard” sub-level) navmesh not work.

“NAVMESH NEEDS TO BE REBUILD” appears on the screen (during PIE,Standalone or Build Cooked Mode).

“Build All” process or simple “Build Paths” not fix that.

Any solution for that problem?

“sorry if this topic is on the wrong place, but i don’t know where search anymore”