Hi Derek - this is how the lesson menu looks for me:
When the page called "terminology" is displayed on the right, its entry in the lesson menu appears in normal font, not as a link. I use the Clean theme by the way. Maybe you need to check your theme if you use a custom one?
I've used lessons in some of the courses I've developed, but these have been somewhat simple lessons with a straightforward flow (no clusters). I've however used questions within lessons and experimented with different flow settings. For example, for a relatively complex question I show the answer on the next page if the student gets it wrong, and for a simpler question the student is asked to try the question again (and is given a certain number of attempts to do this).
To be honest I find the various settings at the Lesson level and the jump settings at the Lesson-page level a bit confusing at times, and my feeling is this is a tool that one needs to keep using to gain some mastery. When I'm away from Lesson building for a while I tend to forget how the different settings work together. I don't have a sample lesson to show at this point, unfortunately.