You can search this forum for users that were able to transfer USD from Paypal to their Revolut card. I remember it being mentioned here before. They might have reported how long it took or you could get at least in contact with someone who managed to do it.
My guess is that it takes just longer than with other cards. Revolut’s platform connects all kinds of different services together, it’s not as straight as just sending funds to a card number that is then connected with one account. I can see that it takes time until a refund is processed by all service providers involved.