Section editing not working for paragraph with h3 header

I've created a page containing only the following (XWiki 2.0 syntax):

= Header 1 =

asdf

== Header 2 ==

qwer

=== Header 3 ===

poiu

= Header 11 =

1234

Once rendered, the page has 3 icons for section editing, whilst it should have 4. Yet the bigger problem is, that when I click the icon next to "Header 11" the editor starts up with the contents below "Header 3".