This seems to be a new issue. I've used course import and 'copy to" to move quizzes between courses in the past and currently, I'm seeing all imports coming over blank, just a quiz title, no questions. This is extremely problematic for teachers sharing content with each other, sharing of district content via Commons, etc. I've put in a ticket but the chat expired before it was resolved (08089367)
update: I'm seeing that the original quizzes have assignment icon next to them and not the rocket ship. The settings screen has the old assignment settings interface before the Build button was introduced. How can we get this updated to a Quiz instead of an Assignment without losing the quiz questions?