“Family has other members”

I am trying to accept an invitation to join a family on family sharing. However, each time I try to join I receive a message box saying “family has other members”.

I have tried:

Settings > Name > Family Sharing > Name > "Stop Using Family Sharing"

Resulting in "Family has other members" alert.

"[Husband] has invited you to join a family" > "Join Family" > "Switch to [Husband's] Family?" (You already have a family set up, but are the only member. Would you like to join [husband's] family instead?) > "Join New Family"

Resulting in "Family has other members" alert.

Software is up to date.

Apps are updated.

I only have one Apple ID.

Thoughts?