Unable to join family in Apple Family Sharing

I'm trying to join a family. I was sent the invite but when I try to press the join button, it says I must be a "member of the family to perform this action." I was previously part of another family, but I left it in order to join this new one. I'd becoming a member of the family not what I'm trying to do by pressing the button? I've tried hard restarting my phone and resending the invite but neither has worked.

[Edited by Moderator]

Original Title: Family sharing issue