I have the same problem. I tried printing a medium sized object three or four times. Each time, part way through the print, the Heated Build Platform would jump over about 1/2" at the start of a new layer. Sometimes it would do it multiple times. It do it on the same layer each time. I tried printer other objects as well with the same results. It started doing this when I upgraded to Sailfish. Before that, I was using the stock firmware. Any help would be greatly appreciated!