I linked Revolut card with my PayPal account. I also have another card linked.
While paying PayPal completely ignores Revolut, just as there was only another card linked and allows me pay only with this another card.
This is a new PayPal account and first card linked was Revolut, but after linking it PayPal behave like no card was linked, so I added another one. I have enough money to pay on Revolut so it’s not a case.
Sounds like a problem with your Paypal account. Many people have linked their card on paypal without problem.
If you can link your card in paypal correctly, but it doesn’t appear after, I would suggest to contact paypal.