Issue Adding HomeKit resident after new Architecture upgrade on IOS 18.4

In case anyone is still having an issue here was my experience. After the 18.4 update a new message appears in settings advising on the HomeKit architecture update. I performed the update on all devices (HomePods/appleTVs etc). Under People in HomeKit settings I saw an invitation for my wife was sent however there was an issue on her HomeKit app saying another Home with the same name exists. To resolve I cancelled the invitation and resent it. She received a new invitation to accept and the home was added successfully. The only issue I had to resolve post upgrade was to re-login to the smart lock app on her phone for her to get control of the smart lock in HomeKit. Hope this saves you guys some headache.