Coincidentally I've implemented some improvements in this area:
- don't try to calibrate a tool until an action button (Outline, Probe, Calibrate, etc.) is pressed.
- redo the tip calibration on the next move after pressing Stop
- remind the printer which tool is attached on reconnect
the first and third improvements will eliminate the error you saw in this case. The second should help you avoid nozzle breaks, if you are hitting Stop. Otherwise, you do need to hit Home if you remove then add the tool after the V-One calibrates the tip.
I'll be releasing a new version of the app asap. In the mean time, using Home will work.
Lastly, i agree than how we display errors needs work. It does the job, but it's one of the few ugly things in our UI. I'm glad you brought it up, since that increases the priority of that work.