Technical Support wrote:
It would not be the Cyber Commander, as it only sends a "fire" command which would be received by all.
Two things,
First, is the power slider of the flash and model lamp set to FULL on the back of the light? If not, it should be.
Second, you were on the right track with a grounding issue. This can come from the mains, an extension cord, a power strip, or even a power cord. If you have not tracked a power cord, you may want to. If you have not removed all extension and power cords, then you should try that.
Have you tracked the telephone cord? And if you are using a cable in the sync jack to disable the
slave, have you ruled a bad one of those out?
I'll review your suggestions. Thanks