Cannot redeem any promo codes - settings urge me to update my (working) payment method

Hi,

so I tried redeeming this Apple Music promo code I got from my local authorized reseller and when I tried to redeem it, the Music app urges me to update my payment methods. When I click continue, my working payment method (I use it for iCloud as well) is listed. I can select it and click done, but the same popup reappears saying that I need to update my payment method.

Then I went to the settings, and clicked my Apple ID to check if anything is wrong there, and yes, under "Payment and Shipping" it says "None". When I click that, I get redirected to the App store, with 2 working payment methods listed (a Mastercard, as well as Apple Pay with multiple working cards added), yet it doesn't seem to be listed in the settings.

I wanted to try re-entering the card I use the most to see if it fixes anything, but I can't even remove it because I have my iCloud subscription tied to it and I cannot cancel it. Lost almost an hour now to troubleshooting with no avail.

Does anyone have a fix for this? Seems like another super annoying bug creeping into production.

Best regards