The Smart tool auto-reverts to the Draw pencil when Tempo View is opened in my Multi-Dock here. I can select the Erase tool, etc from the HUD and they all work as expected. I am guessing only, that this is the intended behavior. Not sure why the HUD wouldn't open at all for you - If it matters, I have my HUD on my Control Bar which is floating below the Multidock, on my primary monitor (dual screens).