ITMS-9012 Error uploading package in iTunes Producer

Hi Everyone,

I have searched everywhere for this error number but can't seem to find anything about it.

We finally completed our book, and filled out all of the required info for our paid iBook (we have an ISBN, tax and operational iTunes Connect account) but when I try and upload the package via iTunes Producer I get several errors. All of them are ITMS-9012 and it follows with this: "No NCX Extension found for NavPoint" and will reference different pages. When I check some of the pages it references there are no superfluous items on the page (and not even any 'links' for the page, some of them are strictly text content).

I am baffled. It took over 4 hours to upload the file and now it seems I need to re-upload but I don't know how to fix the issue before I do. I tried using the Book Proofer app but that seems to only work with non iBA books.

Any help would be greatly appreciated...