Edit: It was quite simply a case of the binding not happening as I expected it. So it was essentially on multi\broadcast out to the world. Once I’d sorted out the proceeding issues it all went away. Saved the summary of the post saved for posterity of my mistake - and someone may hit it on a search when starting out and be prompted to learn from it. N.B. Reloading the device handler does not adjust the bindings, this needs to be done when it joins the network. Does anyone know a method to force a device to pickup new bindings without remove and rejoin?
TLDR: Switch sends command 0x01 to hub, which turns the whole world on. Sends 0x00 and everything turns off. Regardless of using default device handler or a slightly custom one. Is there anything I can change to stop it?