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 To make using Sourcetree as simple yet powerful as possible we embed (bundle) dependencies such as Git, Git LFS, and Mercurial. We strive to keep these...
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