Hi again,
I solved this issue by simply deleting the two problem questions and re-creating them.
When I was creating the quiz, I tried to overwrite the default Quiz with ID=1. When I tried to rename the quiz, a problem with the quiz name kept reoccurring. I kept having to name the quiz and it did not seem to save properly despite refreshing the page.
So, I created a new quiz with ID=2 and reassigned all my questions to that quiz. However, I got the errors that I mentioned in my first post with two questions that I can’t explain. And like I said, I deleted these, recreated the questions and the problem seems to have gone away.
Good luck!