In our project we have many page configurations, with several different contexts for the same page. Sometimes one of the contexts shows that it is “Behind” but when Open Designer is clicked the page does not show the Rebase Pane.
What could be the reason for this?
Note that we also have configurations to the global context, and that one has been set to rebased so it shows up to date. 
The other contexts should show their status based on the modified “global” context is my understanding.

See screenshots.