In-app purchase "Invalid product" on Mac Store build

I wrote a MAC Store in-app purchase plugin (.bundle) for Unity. For testing purposes, I tried using the same bundle in an XCode Mac App project and the purchases worked fine - without the "Invalid product" errors - so the code on the plugin's side is OK. On the other hand, when I use the same bundle as plugin in Unity and make a Mac build (following manual plist edits, code signing through terminal and adding entitlements manually) the purchases always end up with "Invalid product" state. It seems that Unity somehow breaks my Mac build or the plugin .bundle.

Tried many variations of the steps described here:

http://forum.unity3d.com/threads/71340-Submit-Unity-games-to-the-Mac-App-Store!

and here:

http://www.conlanrios.com/2013/12/signing-unity-game-for-mac-app-store.html

and here...

http://technology.blurst.com/unity-games-and-mac-app-store/

To fix my build, but none of the links helped. I can upload the app to the Mac Store succesfully for review, but Apple seems to deny my in-app purchase requests no matter what.

Anyone had similar issues with Mac builds and in-app purchase plugins? Thanks!

P.S. Using Unity Pro 4.3.4