The steps to reproduce:

1. Have the browser window large enough.
2. Find a quiz with several questions, free navigation (for example, quiz "Quiz: Test your knowledge on Alpinism" in the course "Moodle Mountain" of "Mount Orange School" Moodle demo site).
3. Check if the "Quiz navigation" part (navigation buttons, name etc.) is present on the right. (It should be, and it is, if the browser window is large enough.)
4. Resize the browser window - make it narrower, so that the navigation buttons would not fit.
5. The "Quiz navigation" part with navigation buttons is hidden.
6. Make the browser window larger, restore it to the former size.
7. Check if the "Quiz navigation" part (navigation buttons, name etc.) is present on the right. (It should be, but is still missing.)

It would be nice if "Quiz navigation" would reappear when the browser window is again large enough.