This is on version Enfold version 1.3 see screencast attached http://screencast.com/t/f9sWdCfN2oXg
Thank you for the hint. I reported it to Kriesi and we’ll try to fix it in the next version. I noticed this only happens if the link text is empty. For now a workaround would be to insert a link text and to hide it with visibility: hidden
<a id="about-me" style="visibility: hidden;">About me</a>
Hey!
I just checked it. the problem is that this seems to be default behavior of the wordpress editor. When I switch to the default theme and then add a link without link text into the text editor and then switch to the visual editor the link is also gone there. So this is nothing theme related.
You can either use Dudes workaround or use the section element. Each section element gets a unqiue id that you can then use in your anchor text. That way you can also build a nice one page portfolio :)