Share security cameras - no options when click link in invite

I shared my security cam system with my partner. He has registered an account and verified it, including two-fctor authentication. He has received the invite email and it says to click the link to accept or decline the invite. When he clicks the link it takes him to the Shared User's screen and there are no systems listed, so no option to accept or decline. We have waited a day and still nothing shows - it says it should show within 15 minutes.