If you open a Smart Action from the device Buttons menu then exit the Smart Action screen (whether saving a change or just pressing the back arrow), the Logi Options+ application goes to a blank screen that does not allow you to navigate further. The only way that seems to resolve this is to close the current instance and reopen Logi Options+. This error does not seem to otherwise impact the background programs/services since the device customizations continued to work and it seems to save any changes you make to the Smart Action before it goes to the blank screen.