Cannot Add Card for above 13 years old

Hi. There are many similar subjects on this forum but none with a definite solution.

I'm a father of 13yo and 15yo and I manage their accounts. Their Apple IDs were initially created in Ireland, where I believe there is a restriction for using Apple Pay only from 16 years onward.

Since we moved to Switzerland more than 6 months ago, I have updated their Apple Accounts to reflect that change of country. Both their Apple ID settings and App Store correctly show that their country of residence is now Switzerland where Apple Pay should work from 13 years onward. Yet, I'm unable to set up Apple Pay for them.

It's not a bank problem because I cannot even start adding any card in Apple Pay. Whenever I try to add any card, I'm immediately greeted with the message: "Cannot Add Card, payment cards are not supported for this account".

I couldn't find any related parental restrictions configured for their accounts so I'm ruling this one out too. So, if that's not a bank issue, neither parental restriction nor country of residence restriction, my only guess is that Apple Pay system got stuck with the restriction for Ireland, despite we have changed the country of residence.

Could you please help to debug it?