If you are publishing posts to your Instagram account, and they're not appearing in the Posts report, this is likely due to a bug with Facebook, which, unfortunately, they have stated will not be fixed in the short term.
The workaround to resolve this issue is to switch your Instagram account back to a Personal Profile and then reconvert it to a Business Account. Follow the steps in this guide to reconvert your Instagram account to a Business Account. Then, head back over to Publish and try reauthorizing your Instagram account following these steps. We're so sorry for this inconvenience.