Hey charley,
I also was advised to use the firmware 2.8 from the forum : Downloads and Updates for Firmware
This has fixed my z-axis homing problem. The only problem i now have is that the y-axis (heated bed) does not move to its zero point when starting a new printjob.
Temporary fix is to do a manual homing action. Than i am good to go for a new printjob.
Cheers.