Can't see separators on Menu with both skins

You can't see separators. There is a <br> inside the <li> which hides them.

The CSS code that displays the separator looks for 'li:empty', but when the menu is rendered it is transformed to:

<li>
  <br/>
</li>

thus not applying the CSS rule anymore.

This issue is not skin related, since both Colibri and Flamingo skins are affected (since the problem is the rendering).