Ole Gunnar Solskjaer's side are hoping to make the 20-year-old their marquee signing at a time when, given the coronavirus pandemic's impact, few other clubs can get near the Bundesliga club's lofty asking price.
But United are not immune to the Covid-19 situation and Dortmund's valuation of Sancho, widely-reported to be 120million euros (£106million), is a key sticking point.
Sources close to the Old Trafford giants have told the PA news agency that there remains a lot of work to do, with the club willing to pursue other alternatives if a deal cannot be reached for the England international.
The Chile international has been an unmitigated flop at Old Trafford and PA understands discussions over an exit continue, having been given the go-ahead to feature for Inter against Getafe on Wednesday.
United could face Antonio Conte's Nerazzurri in the August 21 finale in Cologne should both sides make it that far in Germany, where Solskjaer expects to stay rather than fly in and out of.
"There's been a discussion at a higher level than me as to how the tournament will pan out," he added. "At the moment it looks like we're staying.
"Of course, you could look at it as just one game and you travel to an away game. But at the moment it looks like a tournament so we'll be staying in Germany."