iTunes Connect error: "An In-App Purchase has been returned"
I had the same problem, following is the screenshot of how my in-app purchase's details page did show a yellow highlighted portion:
What I did is: added another language.. then deleted the previous rejected language, then added the previously rejected-then-deleted language and then deleted the second added language. :-) And it worked!
There is some issue with your binary or metadata that caused app review to reject your app. You need to address that issue. AND: Rather than reject the IAP, app review 'returned' it. If they had rejected it you would have needed to recode a new IAP because once rejected an IAP can't be resubmitted. Once you address the reason the app was rejected, all you need do is open the IAP, add a " " to any field, save it, remove the " ", save it again and it will be ready. I do not recall if you also need to attach it to the new binary or whether it remains attached.
To fix it, I edited >App Store Information >Subscription Display Name, saved the change, then immediately reverted my changes!