Profit loss (P/L) reports are based on the listings close date, not the checkout report run date. For example, if an eBay Stores listing has 100 items and it is set to run for 30 days, and 99 of those items sell on the first day, that Stores listing will not show up in the P/L report until all items are sold or the listing's duration ends. If the last item never sells, then this listing would not show up on the P/L report until day 30, which would be in the next months P/L report.