Why do Blueprints always crash and fail

I am trying to build the world and to test it I have the default third person characte from unreal… but for some reason it always stops working. It works fine the first few times I use it but after I spend some time it messes up and i cant move or i get stuck…

I do not touch the character nor its blueprints the only thing I edit is the camera position but after that it works fine…

With the FPS bluprint it happened too
why does this keedp happening and how do i go back?