The problem occurs mostly, when I am trying to stage hunks containing non-Latin (in my case German) characters. In editor they are visible as "�".
In SourceTree I receive the following error message:
This problem seems do not appear while using git commands git add -p or git reset -p. I can stage changes using terminal, but attempt to unstage it using SourceTree fails also.
Please follow also this discussion.
The screenshot I included in the attachment.