I can open my model just fine, but anytime I select it and either copy/paste or duplicate (ctrl+D) it will partway load, with the error message: "A problem occurred while trying to combine grouped shapes. Please try to group shapes in different order. Check out the FAQ for help. If the problem persists, let us know and we'll help you out!". I don't understand what is going wrong, and it's even more confusing since I can just duplicate the model under a separate design!
Model Resisting Duplication