@Photocoen...In the old days Amazon used to recommend using EPUB 3 format for fixed layout(aka print replica). But now Amazon currently advises and recommends that you should only create a fixed layout ebook using
Kindle Create, which is their own recommended proprietary app for specifically creating fixed layout ebooks(all flavours), reflowable ebooks and paperback books.
And since EPUB 3 ebooks are no longer used and are not permitted for Amazon Kindle upload then there would seem to be little point in making this plugin work for EPUB 3 files. I also know this from helping people on the
KDP Community Forum, where authors are still posting problems after using Adobe InDesign and EPUB 3 format for their fixed layout ebooks, which tends to create all sorts of weird and wonderful errors on upload. The solution to all these EPUB 3 upload issues is usually always to use
Kindle Create instead, loaded with a properly prepared PDF file for all fixed layout ebooks on Amazon.
Prepare Reflowable eBooks and Print Books with Kindle Create
Prepare Print Replica Books with Kindle Create
Prepare Comic eBooks with Kindle Create