Question about royalties regarding returns

On the steam revenue page their are 2 numbers at the top: Gross revenue, and Net revenue. I assume Net revenue is the number royalties would be based off, because it seems like you would not be paying royalties on copies that are returned/chargebacks.

However when I do a date range report on the month of March(which royalties would be based off), and April, It adds up to the Gross Revenue, with no way to see how many copies are returned. my return rate is ~11%, so it seems like it would make a significant difference.

Can someone tell me where I am wrong here, or how to go about accounting for the returns on the royalty form?