Minimized SourceTree Window does not restore

After minimizing the SourceTree Application window to the Windows task bar, it does not restore anymore by clicking on its task bar icon. All I can do is "Close window" from the context menu and restart SourceTree.

This relates to version 3.0.6 which was not selectable in the "Create Issue" window! Previous versions did not have this problem.

[Update] I've updated to SourceTree 3.0.8 and the problem is still there.