Wanhao duplicator i3 plus mark2 - leveling problems

After I have loaded the new firmware, the bed does not want to level. With the old firmware I had the problem that I had to re-level after each print. It is not a hardware error, because with a caliper I checked before and after the print job and no value was changed. Automatic leveling does not work either. The latest version of firmware is I3PLUS-2.0-V1.02. The seller searches with me for the cause and solution. But do you know what can be wrong?