Good solution, because it works
You will not see your lesson if you are in the lesson and it is the only one in Topic 1.
Too many "jump to" places. Realized you were referring to the drop down at the top of an activity module, such as lesson. So I went to demo.moodle.org. I went into the Lesson as Admin, and looked at the "Jump to" pulldown. All the topics (showing just the topic title - which is probably Topic-1 for you) are there with the activities located under that topic/section/week. However, in the Lesson, there is only one activity and thus the only thing I saw in that topic was the Lesson icon and the labeled "Jump To" again.
Hope that helps. Chris