If you want the Navmesh to be affected by an obstacle that wasn't baked you have to add a Nav Mesh Obstacle component to it, and set Carve to true.
That doesn't have anything to do with Playmaker though, I suggest you go through the link I posted earlier and try to understand how Navmesh works.
And like I said, the related actions are pretty straight forward, but Playmaker actions don't always exempt you from having to understand the tools you are using, which is what I think you're having trouble with.