When using remote desktop to access my PC to deliver training, I have been bummed in the past to notice that linked modeled objects did not show up on the display screen. They are there, and if I went back to my PC I could see them. In fact, if I selected a window, Revit would tell me that I have selected objects.
I found out later that using or not using hardware acceleration caused the issue. If the same happens to you, make a change in the Graphics tab of the options dialog and reopen Revit.
Now everything should be visible and the training can continue.