Invites to External Roles not being received

Under User Management > Roles > Role Members > Click 3 dots at top right > Invite external users to this role

I invited 3 emails - all same person - only 1 of those emails received the invitation - the email they least wish to use because it is their company email and not their personal email address. All 3 are gmail accounts. 

I even added my personal additional gmail and never received the invite either. I have no idea how to correct this.