Hey!
Sorry for not getting back to this post. Yes, I did check this scene - and it does behave weird, but this is expected from the way it is being used 
A groupd should be, well, a ground. You are using a complex model (the house) as a ground. If you expect to be able to teleport inside the house by just providing the house as a ground mesh - it won’t work as expected. You will either need to generate a new mesh for that, or separate the house to ground and walls. The 2nd floor can also be a ground mesh, of course.