Why does nouz say my CM1 is overstated?

Because something you sold has no unit cost. Rather than treat a missing cost as zero, which would make the margin look better than it is, nouz counts the affected units and says so plainly on the page.

The warning links straight to the products involved, so closing it is a short session of typing costs rather than a hunt. Once every sold variant has a cost, the flag disappears on its own.