Great point. Using the "marker 4" example...the title shows up dramatically mis-styled from the other items (markers 1-3) in the menu. The link is not active (i.e. no cursor change on hover etc), and does not "go" to my marker 4 marker. Hope that helps. In short no aspect works.
Great points Jerome and Zeebe. However, my page is tall enough for the scroll to occur and I do in fact have a correctly named marker 4 in my layout.
For another bit of the mystery. If I copy and paste the existing code (that contains markers 1-3) they appear in duplicate, and function in duplicate. For instance I would have six links (1-3 and 1-3) that all work and display as they should. If I change the numbers in the exact code that I've copied (3 to 4 for instance) that item that I've changed reverts to the non-functional behavior described above.