I am running Sourcetree for Windows 3.4.3 (Enterprise).
I upgraded to the newest Git for Windows version, 2.31.0. With that upgrade, the "Terminal" button does not work anymore for Git Bash, i.e. nothing happens if I select it. If I disable "Use Git Bash as default terminal" in the options, it opens the Windows command prompt.
With the older Git for Windows 2.30.2, it worked.