Instant sales reports are a relatively new development with the advent of e-publishing -- so I guess I should be grateful (and I am) -- but there appears to be a lot of confusion over just how "up-to-date" the KDP sales reports really are (here and here, a google search yields much more).
I was under the impression that sales reports would be instantaneous (and maybe I was naive, but this myth is perpetuated by a large number of bloggers, so it's not entirely my fault). The fact is, KDP sales reports are rarely instantaneous, and often times can take days to update (and this is when things are running smoothly). A recent KDP outage had many, including myself, waiting for almost a week before seeing any update to our sales. And outages are more common than you think.
My point: Don't go into KDP and expect up-to-the-minute sales reports. They don't exist. Just sit back. Relax. And stop checking your dashboard every 5 seconds.