Does Kindle for iOS v4.5.2 (latest vers) actually support images up to 5mb or not?

Publishing a reflowable book using Sigil v0.8.1. The ebook is a travel guide that requires two map images larger than 127kb (specifically 1.24MB) in order to see details when zooming. There is absolutely no way to cut up the image or reduce the image size any more than we already have so we planned on taking advantage of KF8's "up to 5mb" image support.

I performed a simple test using Sigil to create a reflowable .epub with a chapter of text and two 1.24MB images in order to determine the outcome on several devices.

From the .epub I generated an .azk file using KindleGen (v2.923), then using iTunes I sideload it directly onto an iPhone (iOS v7.1.2). The iPhone is running Kindle for iOS v4.5.2 (latest vers) which supposedly supports KF8. The test book only shows the compressed <127kB image no matter what I do. If I use Kindlegen however to generate a .mobi file with the same content then load that .mobi on an Android device the 1.24MB images are used and view fine on Kindle for Android. The question then is does Kindle for iOS v4.5.2 (latest vers) actually support images up to 5mb or not? We have to know before we proceed.

I emailed Amazon KDP support several times and each time received a canned response that had nothing to do with my above question.