Another thread seems relevant:
So, I'm guessing the Node Information Frame is the broadcast message, as @martyn suggested above. He mentioned that he believed there was some change related to NIF processing between C-4 and C-7 or perhaps different revisions of the platform firmware.
Could someone from Hubitat please confirm/deny if there was a change to NIF processing? If there was, could it be reverted in a future platform firmware update? If there wasn't, could NIF's get passed to the driver-level for processing in a future platform firmware update?
I can certainly understand Hubitat's position that these devices should operate differently and that it is their responsibility to send timely reports, but it feels like this is not some isolated issue related to a specific model or even manufacturer. And, since I have not seen widespread usage of OTA updates, I think the devices are what they are.
As I mentioned, this is something that makes Hubitat unsuitable for this use-case (no-load/remote switch), with this device. Admittedly, this is probably not a common use-case.
Thanks to all who have helped hunt down what is going on here and apologies for the lengthy thread. I've learned a lot.