As I couldn't find any solution to this when browsing the forum, I think I might have found a bug - however, this seems to have been already here for quite a while as it was already in 0.12 and in the current 0.13 beta release.
The problem lies in the default menu: When I use the menu on the left hand side, separators are not shown, when showing the menu on the right hand side, the separators show up. Now don't think I was messing up my installation...

I did a test straight after installing and I had this effect already in the default CMSMS installation.
Hope this helps - I would be pleased to provide any more information if required, however, it seems to be pretty easily reproducable...
Thanks for this great piece of software!
Pat