There is a bug reported into Atlassian Bug Tracker (jira.atlassian.com) that seems to be the same that you're facing:
This bug is fixed for the next SourceTree release. Could you please check if is this issue that you're facing?
Supported Platforms macOS Windows We recently introduced support for additional hosting services such as GitHub Enterprise, GitLab (Cloud, Community Edition, Enterprise Edition), and...
Connect with like-minded Atlassian users at free events near you!Find a group
Connect with like-minded Atlassian users at free events near you!
Unfortunately there are no AUG chapters near you at the moment.Start an AUG
You're one step closer to meeting fellow Atlassian users at your local meet up. Learn more about AUGs