@Rick - when I am logged in as a teacher and I click on a Quiz, I see the Preview button like this...

Ok assuming you have admin access since you added the quiz to the front page, can you access the front page question bank, select and move the questions to the "Default for system" and then go into the course, set up a new empty quiz and from Add a question from the question bank, see if you can locate the questions in Default for system (as I did one question here)...