The number of people (kids) in terrible 3 and 4 person guilds of inactivity that spam you with hundreds of invites is ridiculous. The block option needs to block all of the activity of that player.
If you block a person. They can’t access your profile. So they would have to have your invite code. If you know the person who is harassing you then submit a ticket.
If they can still see your name in chat it obviously still works
For the block to take effect. You have to restart the game.