I have been using GitFlow integration with SourceTree on Windows 10 x64 without problems, until I recently upgraded to 3.1.2.
Now, when I switch to the master branch, and go to the GitFlow actions menu, there's no Create Hotfix option, just Finish Feature and Other Actions. If I go to Other Actions, I can see Create Hotfix, but when I click that and give a hotfix name e.g. ABC-123-fix-this-bug, it creates the branch without the hotfix prefix i.e. master -> ABC-123-fix-this-bug, instead of master -> hotfix/ABC-123-fix-this-bug.
If I then create the hotfix manually by branching from master, and I want to finish the hotfix, the Finish Hotfix option is again missing from the main GitFlow menu with only Finish Feature being present. If I go to Other Actions, then Finish Hotfix, it brings up the dialog, but after a second or two, clears the hotfix/ABC-123-fix-this-bug entry from the dropdown and gives me an empty dropdown box, so I can no longer finish the hotfix.
I haven't tried creating/finishing releases, but I am not full of confidence...