I think you have not added any dashboard widget in it.
Please set the dashboard widget. Refer: http://prntscr.com/od4811
if it is set, please open all the widgets above and check their respective settings.
If still, you are not able to solve then please share temporary admin credentials in private reply.
You are right. The student and instructor sidebar was empty. Can you show your instructor sidebar, please? (similar to student sidebar) I want to see the default widgets.