Hello @sholzman
Thanks for posting this in the Community! I apologize that you are running into issues with the reporting for your New Quiz.
As mentioned previously, It will take up to 24 hours for quiz information to display in New Quizzes reports. Sometimes you just have to check back after about 24 hours from the time the last submission was received. Because of the complexity of the issue, and the concerns for privacy, it would be best if you contacted Canvas Support directly to pinpoint the source of the issue and provide a resolution.
Let us know what you find out on this!
-Colton