Parts disappearing, is this a bug?

I'm following this tutorial and following it exactly. I've made the exact same drawing so far, exact same constraints, and getting the exact same results until now.

At 13:22 he uses the Pad tool to extrude a ring, and then confirms it. The result is that he has basically built a flange with a hole down the middle.

When I confirm the extrusion, everything disappears. It still shows up in the model box, but I can't see or interact with anything in the main window, and I don't get any errors or notifications.

I can keep sketching, but everything I've done up until now is basically gone. Is this a bug, or am I doing something wrong?