Syntax errors could be a problem. I suggest using EpubCheck.
There is
a plugin for Sigil that allows easy adding of page numbers to an EPUB.
Adobe has their own proprietary method of defining pages using a
page-map file. ADE may be looking for that.
If your document is EPUB 3 then the page-list in your NAV document will be used instead of the NCX pageList.
The Kindle Previewer does not show page numbers, only locations.
Amazon can make use of a page list that is properly encoded in an EPUB source document. I haven't heard of Amazon automatically adding page numbers. Perhaps someone more knowledgeable about the Kindle publishing process will comment on this.