I reached out to a member of Una Voce St. Paul and Minneapolis to confirm and the Mass has indeed been cancelled. No other details were provided.
As Tancred pointed out, the Cardinal will be at the annual meeting of the Equestrian Order of the Holy Sepulchre of Jerusalem. The meeting takes place in Minneapolis at the same weekend of the planned TLM at the basilica. I think the Cardinal is attending at least part of the conference but the order will be making a pilgrimage to the Guadalupe Shrine in La Crosse the following Monday. This is a great group that assists Catholics and the holy sites in the Holy Land.
The point is, it seemed to make sense to schedule an event while the Cardinal was in the area, so it is left to speculation as to what occurred here.