VUE has no idea? Really?
Both VUE and Prometric were invited to tender for Microsoft's new single-vendor exam system.
VUE claims they don't know why they didn't win the tender, but is that so unusual? Tender losers aren't always told details of *why* they lost, simply that someone else submitted a better bid.
The fact that Prometric is regarded as the inferior provider by many due to poor customer service and technical problems, yet still won this tender, is a source of heated debate in insider circles.
Regardless, Microsoft's decision is final, which means for better or for worse we're stuck with Prometric... until Microsoft changes their minds again :-)