SourceTree disappears when using "Checkout in Sourcetree" link from Bitbucket

I recently updated to SourceTree 3.4.2 and now when I try to clone a branch by clicking on a "Checkout in Sourcetree" link from our Bitbucket server, SourceTree simply disappears.  I get the normal "URL Actions" window, and when I click Checkout (or even Cancel) the application simply closes: no error message and no crash dialog.  When I re-open Sourcetree, the new branch has not been checked out.  I've been working around this by checking out the branch from the "Remotes" node in the left hand pane.

Is there any kind of log file that I could provide to help debug this problem?  I looked in C:\Users\<username>\AppData\Local\SourceTree and did not see anything.