This is directly tied to the fact that Microsoft is converting its derided Microsoft Points system in favour of various local currencies. "With all these changes, it's become necessary for us to evolve the way we reward you," wrote Microsoft in a statement.
But worry not! For Microsoft insists that a variation of the program will be reinstated on 1st September that will have "even better" rewards.
"Since this currency change is impacting the structure of the program, we're taking the opportunity to make Xbox Live Rewards even better," Microsoft continued. "You'll continue to get rewarded for doing the things you love on Xbox Live - just not with Microsoft Points."
Microsoft noted that everyone will receive their pending points on 7th August, at which point they can either spend them or wait for them to be converted into local currency in September. For additional info about this transition, check out this handy dandy FAQ.