Crash when open level

I’ve a problem with the open level feature.
My current game crashes when opening a new leve via “open level” in blueprints.
So I tested it with a blank new project, created two default levels, LevelA and LevelB. In the Level Blueprint I created a open level node references to the other level.
When I start play and I press the key 1 the engine stop working and freezes.
Interesting is, when I load the project and start the game for the first time, the level loading works perfect. When I go back to editor and start the game again, the engine freezes.
I also tested it with 4.18. It’s the same problem.
I switched off the Computer firewall and closed antivirus but nothing changed.
Does anyone know this problem?