Hi - I have been some messing about and have found that only when the Azure invite is redeemed and the user goes from being 'Invited' to 'Guest' user or simlar in their profile can you add them to a SharePoint Online security group.
This is an issue for us in our scenario. I wonder how we can know when a guest user has redeemed their invite so that we can add them to the SPO security group. I know this is not a mature product yet - but I really want to use it and its being a bit of a pain! thanks