CVV button remains greyed out on child account when trying to verify

I added a new card to my account and removed the older one , this card shows that it is linked with family sharing , however, when I go to my child's iPad (9th Gen) to verify the card by adding the CVV, the done button remains greyed out even even then I put in the cvv.

Initally I had disallowed accounts changes on my child's account but when trying to verify the card, I had changed it to allowed , still the done button remains greyed out. Have searched the forums but no one seems to have reported a similar issue, and most say the oraganiser needs to add the card in their account first (which is what I have already done) , any advice will be great.