World composition with navmesh - no green area at all (MoveTo aborts)

My current project is made from 3 levels: Persistent Level (root), one MainLevel, and the other NotUsedLevel.

In MainLevel I have a landscape (64x64), a player and an npc, and a nav mesh bounds volume.
However I can’t see the green area on the landscape when intersecting the nav mesh bounds volume with the landscape.

I also tried (as suggested online at some places) to create a navmash at the persistent level, but it didn’t help; I still don;t see any green area. What am I missing?

p.s.
I’m looking for the green area as an indication where my npc would be able to go; currently, I’m just getting movement aborted when trying to tell it to move

It seems restart did the trick, not sure what was going on.