I have this issue. When I originally set up my Apple Card I did not have this issue and could see my card number in the ‘Card Information’. About a week ago I had to reset my iPhone and reinstall my cards in Wallet and that is when this problem stated for me.
When I went to ‘Card Information’ to get my card number and details to use the card number manually I received the error, ‘Account Services Unavailable. Apple Pay services are currently unavailable. Please try again later.’
I have an open case and the support representative was very nice and told me this is a ‘known issue’ and ‘Apple engineers are aware and working on it’. However, she did not have any suggested workarounds. She took my information and had me reset my phone and do several steps but nothin worked. She then set up a call with me a week later to follow back up.
After reading these posts I tried to add the card a second time and I now have two Apple Cards in my wallet ... And it works now! I can see the manual card number in ‘Card Information’ on both Apple Cards. However, one card reads ‘this card cannot be used. Remove this card and try adding it again’. This card that is not usable remain the standard white color and does not have purchase details on it (but I can see my ‘Card Information’. The other card has the colors from my purchase categories and is completely usable and I can see all my purchase information, etc.
...For me the two card ‘work around’ is successful and the unusable card is the card that iCloud will repeatable install when I try to add cards into my Wallet.
My ‘guess’ is somehow the backend systems have associated the card details and my iPhone serial number and SEID (the support representative asked a few times about my SEID) and that ‘original’ card configuration is needed in Wallet to see the card details in Card Information.
Anyway, workaround with having two Apple Cards in Wallet worked for me.
Hope this helps others.