At some point something happens that causes the homing sequence to stop and the only way I have found to recover is to replace the xml file with one that was backed up when the homing sequence worked.
Some additional troubleshooting steps I have tried. Disabled and then re-enabled the home switches disabled shut down then re-enabled, disabled shut down rebooted then re-enabled. Reinitialized the usb breakout board. No luck
I have not had a chance to verify this yet but it seems that after I have gone to the toolpath tab, run the road runner gcode a few times, this problem occurs (by the way I have made a few beautiful road runners). If I go back to the main page and the problem exists. I hit ref all home and the leds flash red then green the dros do not change and the axis do not move. If I go to the diagnostics page none of the home switches are active. If I try to home each axis individually I get the same result, the home led flashes and nothing else happens.
Next time this happens I will save the 'defective' xml file and then try to compare it to the working file to see if there is some difference.