After discovering that my iotawatt was stuck in a reboot loop, and fixing that issue, my Home Assistant integration now seems to be working fine! Fingers crossed that this lasts.
I will be much more conservative about HASS software updates in the future 
Home Assistant 2023.8.2
Supervisor 2023.10.0
Operating System 10.4
I haven’t been able to update past HA Core 2023.3.1. My IoTaWatt HA integration fails if I do.
I have zero clue on how to resolve it.
I am wondering if any developments are in the wind to resolve Wattmatters issue (only his?), or the impasse with HA over unique IDs. A comment on the inbuilt repository suggests it is not being maintained.
So what is the recommended solution for HA … custom (Kuralabs) or inbuilt, or something else?