Hey -
I tried to create a new actor class as well as a blueprint based on it and other blueprints each bases on the new BP before it. This created a hierarchy chain starting at the new class and ending at BP5. After creating multiple levels I tried to switch between the levels in the editor and did not crash. Are you referring to switching levels within the editor or in the game itself? Also, would it be possible for you to send a sample project so I can see the crash directly? If you can’t get the crash to reproduce in a blank project you can upload your current project to dropbox and send me a private link on the forums.
Cheers