UE4 - Navmesh stops working after Level Streaming, why?

HI, I created this landscape into a level, once character gets closer it loads the level (level streaming), Nave mesh is located in the persist. level, But… sometimes, “some” of the AI actors, like 5 out of 10 can’t move, the try, start rotating in place, run the walk animation but they cant move, while others do (all of the same level), If I get out, “unload level” and move closer again, now other actors have this issue, it´s like if by Level Streaming the landscape and actors, they “sometimes” fail to use the nav mesh, weird, like a bug in UE, I’m certain my crown manager options are fine, I even raised the max amount from 35 to 5,000 as a test… still failing sometimes,

I’m no sure why or what to do, if I press “p” everything is fine, nav mesh is correctly placed over the landscape, building paths works correctly until some AI’s can’t walk, I always test this after packaging.

Please help.