Unable to export a valid ePub 3 Fixed Layout for being used on iBooks, Google Play Books and Amazon

It's been months since I started trying to export my PDFs as ePub 3 Fixed Layout (to preserve the original layout, as it is like a magazine) though InDesign to sell it on Apple iBooks, Google Play Books and Amazon, without success. I exported it using the Export as EPUB (Fixed Layout) option.

• For iBooks, when I upload it using iTunes Producer, it return a number of errors (including multiple instances of "Referenced resource could not be found in the EPUB", "Error while parsing file 'value of attribute "href" is invalid; must be a URI'.", ""Images larger than 4,000,000 pixels are not allowed in books.", "...is not a valid URI.") and can't upload.
• For Google Play Books, it shows the same errors as listed above, and can't upload.
• For Amazon, it successfully uploads the ePub, but when you open a quick preview or even buy the book, it displays a broken layout, it's impossible to read. file is listed in the OPF, but is missing from the EPUB.

Apple asked me to contact Adobe support, but the person that I contact didn't have any idea about this and just sent me some unrelated Adobe Help links, and in the end said that its a problem with the platform I'm trying to upload the EPUB. Apple also asked me to check the file with the EPUB Checker app, and it displayed the same errors I mentioned before (screenshot attached). So although the file can be viewed perfectly in epub readers installed locally, it definitely looks like InDesign is generating an invalid EPUB file that cannot be uploaded to stores. Unfortunately I couldn't find any information elsewhere that helped me with this, so I ask for your help.

Thank you!