The In-App purchase section will not appear if you do not have at least one in-app purchase with the status "Ready to send" on the "Features" tab in the "In-app purchases" section.
Since your shows are “Ready to send,” just go back to your app’s page, open the “Prepare for sending” tab on the left side of the screen and scroll down until you find the “In-app purchases” section, It’s located directly under the general information about application.
I had several listed there, but each of them was missing a photo, so their status was "Missing metadata" instead of "Ready to send."
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