Hi 
I know this is not the answer for your question, but do you need “dynamic” grid obstacle? As far I remember DynamicGridObstacle is refreshing every X seconds (please correct me if I’m wrong)?
What do you want to achieve exactly?
In my project I have gates. Whenever I want to open them I set grid under the gate to “walkable”. If I want to close them I set this grid to “nonwalkable”. I can consider it as “dynamic”, because they changing pathfinding realtime.
Here, I have posted some code that I’m using to do that:
Maybe that will be enough 