The “Make Group” command functions without a selection, and it causes your model to simply vanish in this case. It’s quite a shock when you’ve mapped this command to a shortcut and then hit it by accident, only to see all your work vanish in the blink of an eye.
This isn’t a crashing issue, and the work-around is to simply undo once you realize what you have done. But it’s a bit distressing, and it shouldn’t happen. The Make Group command should probably just beep with no selection present.
Maybe Colin can add this one to the to-fix list