Using Git.
I have a change staged to the index, and more changes that are not staged. When I click on the staged file in staged file list of the working copy or the unstaged file in the unstaged file list, I see differences between the file in my working copy and the last commit. Previous versions of SourceTree were able to show me the staged differences separate from the unstaged differences.
This appears to also be affecting the ability to stage or unstage hunks or lines.