can't invite others to home hub

i have set up a home hub using one apple id on my ipad, I am able to view the Omna camera with all the devices that are using the same apple id. but here are the problems

1) I can't invite other using the ipad. everytime I sent an invitation from the ipad, I do not receive it on my iPhone (both ipad and iPhone are on the latest software)

2) I can invite via another iPhone (with the same apple id as my home hub) and successfully accepted the invitation on my other iPhone. I can view the Omna camera while in the house via wifi but am not able to view if i'm not on the same wifi network

Please help to resolve this.