Alters rally joining question

Hi, I hope I'm asking this in the correct area of the forums. During the Altar events, I am able to capture alters and join clan member rallies for the altars but clan members cannot join my rallies. I've participated in many altar events and the first time I participated clan members were able to join my rally but now aren't able to. Is there a reason for this? Could someone explain why all of a sudden no one in my clan can join my rallies? Thank you in advance.