"Couldn't Add Accessory: Home couldn't connect to this accessory"
Anyone else experience that?
Best answer by jamus
Apparently, adding this type of accessory requires being added by the original account that setup the home, not any other accounts that the home may be shared with (even though they have full permissions). Once I logged into that iCloud account from my phone, and rebooted the phone, I was able to add the device first try. Before that, I tried rebooting the phone, trying another phone, rebooting the device, etc.
What led me to try the different account was looking at the device logs via the Console app and came across an error "Must be owner to add WHA accessory" from HomeKit.