IAP rejected (Guideline 2.1) while binary waiting for review?

That's a new one for me. I have submitted 2 IAP along with an update for my app. The Mac binary was approved but then one of the IAP was rejected with this message:

"We have returned your IAP product/s to you as the required binary was not submitted. When you are ready to submit the binary, please resubmit the IAPs with the binary."

I'm not sure what this means as the related binary is actually waiting for review.

What does this error means and how can I fix it?