I think we're saying the same thing. If the power is shutting off to the IC60, it's not the IpH doing that, they'd both be going off together. I gave the OP a troubleshooting tip to determine if that's what's happening. Otherwise, it's some sort of errant command that is triggering the re-run, and I suppose that could be any of the electronics involved.All the make sense, but the com port is not going to shut off the IC60 or the IpH by removing the DC power..
If the OP has checked all the wiring connections (cleaned and shiny), your idea to take the IpH out of the loop is the next step. That would narrow down the culprit list with very little effort.
OP, as always, be sure all the breakers are off before disconnecting any cables running between IC, IpH and controller.