For anyone that is having issues with the probe/ levelling on their printrbot metal...
Remember to add Z0 to under "scripts" in FFF settings.
By default its:
G28 X0 Y0 ; home X and Y axes
G29 ; probe Z
It should be:
G28 X0 Y0 Z0; home X Y and Z axes
G29 ; probe Z
I just picked this app up today. Wish I had bought it a long time ago, it rocks!