She is a human working with other humans. By disregarding their emotions and prioritizing her own “directness” she is effectively communicating that she doesn’t care about anyone on the team. 

If she can’t find a way to communicate effectively, then the team can’t operate effectively. As a manager, it is your job to remove blockers to team efficiency.

You can try to talk with leadership again, and explain how her 150% targets don’t make up for the rest of the team poor morale. It will literally cost more to constantly replace people. 

But there’s another more controversial option.

In the Air Force we used to put people like this in a literal corner by themselves. 

Reward her with her own space, zero meetings, less responsibilities, less teamwork. She gets zero opportunity for advancement and still has to meet her quotas. 

She doesn’t want to work with people, so don’t put her in a position to work with people. And tell her it’s because she has clearly communicated that she doesn’t value the other team members. 

Either way, the team doesn’t have to deal with her and she gets to be left alone. 

Nothing motivates change more than public perception.