Bitbucket "Check out in Sourcetree" no longer working

The "Check out in Sourcetree" button on a branch in Bitbucket suddenly stopped working for me at least as of version 3.0, same problem in 3.0.1.

When I click the button it opens Sourcetree, but it does not check out the branch. Trying multiple times makes no difference. Restarting Sourcetree does not fix it.

Copying and running the git terminal command provided by Bitbucket still works, as well as switching manually in Sourcetree.