Navmesh with Vegetation

I've been searching the forum, and using Google, but I can't find a solution to the problem.

How do you generate the Navmesh on a terrain with vegetation?

We tried to hide the objects in question but Navmesh picked them up anyway. We had to delete the objects in order to get Navmesh to work correctly. However, that's a very undesirable approach. Can we layer the items on the terrain?

Anyone?

Thank you in advance for the help.

 

Is anyone familiar with Navmesh?

I think we'll switch to a pathfinding algorithm because Navmesh needs to be regenerated whenever the scene changes, which is time consuming, and can be a big delay between changes and testing.