Often Clickbank makes a periodic maintenance, so clicks are invisible at that time. You can wait for 24-48 hours, and then statistics will return to normal.
You want to do a test purchase at that time just to be sure and see if you get credit for the sale while checking Clickbank's Status.
Anyway, I asked our Vip guy at Clickbank and here's what he got for us:
"Hello,
I apologize for the inconvenience. Unfortunately, our analytics are currently being worked on by the IT department. We are aware of the discrepancies and are working on a fix for them."