Open Roads Designer Freezes/Crashes when deleting or dropping terrain models

I have an OpenRoads Designer dgn Version 4 with several terrain models.  I am editing the terrain models and adding new ones frequently.  When attempting to delete the terrain models, or when using Drop Element, ORD freezes up and I have to kill it via task manager.  

I have tried detaching source files, removing rules, and removing templates or feature definitions.

I am running Windows 10.

Anybody know of a solution or cause?

Thanks,

Jason