I've had the similar problem since Feb. 10. The total numbers of usage (downloads, streams, subscriptions, enclosures) of individual collections/courses of each week exceed the weekly sum. Furhtermore, the Browse category has zero in each individual collection/course even though the weekly sum has tens and thousands, which has been the case until Feb. 10.
So it appears the problem exisits in the individual collection/course usage data.
The individual collection/course usage data is what I use to report to the insitution's content developers each week.
Hope this can be fixed soon.