If the menu is missing from a course, it might be because the course menu frame became hidden. You can expand or collapse the course menu frame by hovering your mouse in the course menu frame which will make visible a thin gray line to the right of the course menu frame. Once on the gray line, your cursor will change to an arrow and a tooltip stating “Show Course Menu” will appear. You can click on the arrow and the menu should re-appear.
If the issue persists, consider further troubleshooting steps in the following video: