Can’t invite family HomeKit

Invite someone to control your home

1. Open the Home app on your iPhone, iPad, iPod touch, or Mac. Tap or click Home, then select Home Settings. ... 
2. Tap or click Invite People.
3. Enter the person's Apple ID that they use with iCloud.
4. Tap or click Send Invite.

Share control of your home - Apple Support

Having the same issue - and this advice is insufficient. While I can invite my family members the invite seems to spin and hang on their device (all updated to latest ) showing only the cancel button but not the accept invite button. Furthermore, when I invite my wife she appears to become the primary owner while I then then become the resident. That is very strange. Nothing seems to work and I’m unable to connect multiple family members to our home.

I have the same issue. There are other complaints for years about this issue with no solution. Infuriating!