Navmesh Modifier Volume Problem

Hello, i have a dynamic NavMesh with is genarated only around Navigation invokers. Works fine. Now i want exclude a water Volume. I build a Navmesh Modifier Volume a filter Class and area class. I put the Volume into the level add the class. The color of the navmesh dont change. (i added red at the area class) OK i run the game nothing happens. I try many thinks nothing works. The Modifier Volume is no active. If i change at runtime isActive to true it works fine. What is to change that the modifier volume isActive?

Anybody can help?

After 2x restart the Editor it works.