I’ve done a brief research, and found no similar thread, so im sorry if you already know about this (Im attaching a GIF to be more clear):
As you can see, when you click on the element above “Responsive Web Design Projects”, with the object spreaded, this element disapears.
I know you are working on this section, but i hope this helps if you dont know already.
I’ve tried to find the problem myself on the HTML, but it seems that the < li> element is actually missing.
P.D.: Thank you for your time and your unpayable work.