welcome to the Atlassian Community!
Could you please check if there is an error logged in logfile for Sourcetree? If so, could you please share it here? Community members familiar with Sourcetree have then the chance to check if the issue is known to them.
You can find the logfile location as outlined in this article:
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 an event
Connect with like-minded Atlassian users at free events near you!
Unfortunately there are no Community Events near you at the moment.Host an event
You're one step closer to meeting fellow Atlassian users at your local event. Learn more about Community Events