It happens occasionally. I'm guessing that the sales number for each game have to be manually entered by ioi, so he may be doing adjustments. The Dragonball game was missing some numbers from some regions (or possibly undertracked or overtracked), so ioi might be doing adjustments. Link's Crossbow Training is pretty similar. This has happened several times before (Red Steel, for example), and the numbers always come back.
No need to concern yourself
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