Hello @SaraHoeft74
Under edit, the quiz has been assigned to "everyone" and nobody has been singled out? Under the 4 questions - are any of them set to pull a certain number from an item bank or are they all here individually and not linked to any item bank? If all settings like fine and there's no setup with a item bank (as it could be pulling blank questions from the bank for students) you may want to contact Canvas Support.
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:
https://community.canvaslms.com/t5/Canvas-Basics-Guide/How-do-I-contact-Canvas-Support/ta-p/389767