The Bundesliga club have now appointed an agent to sort out the details of the transfer fee.
United want to pay an initial £70million that could rise to £110m based on honours and appearances. But Dortmund want more upfront for the 20-year-old England winger.
The player's representatives are now looking for more upfront in wages too.
The club want to offer a highly incentivised deal worth £220,000 per week. But Sancho is holding out for closer to £250k.
Again this is proving a sticking point with Sancho's side.
The Red Devils are also unhappy with the agents' fees being asked.