Ole Gunnar Solskjaer has identified the 21-year-old as a key signing this summer, but initial hopes that the player's openness to go to Old Trafford could lead to an uncomplicated deal have been misplaced.
Palace feel under absolutely no pressure to sell Wan-Bissaka, and would want a fee of over £70m to even consider the prospect.
United had been hoping to complete the signing for at most £40m, but that now looks way off.
It is understood other clubs have already been put off by such a high valuation, but United will persist with the pursuit.
United are set for a busy summer with central defence another area identified for reinforcement.
Kalidou Koulibaly is a long-term target but Napoli's asking price makes Leicester City's Harry Maguire potentially an easier deal to do.