Hi all, this is a known bug that has been fixed for the next update. Sorry for the inconvenience! As a (sort of) workaround until we push, if you keep loading/closing Stonehearth, you’ll usually get it to work.
(Long-story short: we changed the way the UI loads, so it loads while the rest of the game loads. But what can happen is that the game can tell the UI to open the main screen, before the UI is even ready! The UI doesn’t know what to do, so it does nothing, and then the main screen never comes up 
We’ve had a number of UI-related issues this release, due to our Chromium upgrade. Sorry for all the churn!)