Actually, they’ve had that calculation message on there for a very long time, it’s not new. But hard to say how they use it in their calculations. As for ratings without reviews, I see that occasionally (also not a new issue) but eventually it seems the reviews do catch up. I suspect it likely has something to do with how they run things on the background with multiple servers and such, some get updated before others, etc – causing issues with data not being synced up properly on the front end. But again, just a guess since Amazon never really tells anyone anything for sure!