App won't restore after being minimized

I updated SourceTree on Windows to 3.0.6. The app window comes up OK when first launched, but if I minimize the window, then I can't restore the window, either by clicking on the icon in the Task bar, or Alt-Tab switching to the app. Nothing I do will restore the window. I need to quit the application (e.g., with the Task Manager), then restart the app.

According to the About dialog, the version is 3.0.6, although the bug report won't allow me to specify this. The largest number I can select is 3.0.5.

Also note that I had been running SourceTree 2.x on Windows, and was prompted today to update to 3.0.6. I had not been running any version of 3.* prior to this.