My app Manga Blitz (com.mangablitz.app.kindle) is only available on Non-Amazon devices, every update I've submitted seems to fail with N/A for comments. But the latest update has passed however it only has Non-Amazon Devices listed as being tested. It's still not available in the App Store for my Kindle, though the device support in binary tab still lists it. Has it even been tested on Amazon Devices? I've removed everything I think would cause a problem and it works perfectly fine on my test Kindle.
Joshua, Thank you for your submission to the Amazon Appstore. We consider a variety of factors as we evaluate each app, including the customer experience offered on the device and compatibility with the device. While our goal is to offer a broad and compelling assortment of apps to Amazon customers, not all apps available through Amazon Appstore are currently available on Amazon devices. We believe your content is better suited for publication on our Kindle eBook store. Please submit your content at Kindle Direct Publishing.