(took a look at the files that were sent)
In this case, I believe it is simply that the browsers have a lot of processing to do on the images, and can’t load and display them fast enough before showing a blank (white) area. You’ll notice that if you make the window smaller (or disable flexible layout), the flashing will go away because the browser has less work to do in scaling and putting the pixels on the screen.
There’s no specific trick that will help, but there’s a few things you could probably do:
Use smaller images. The images are currently 2500x1669, which is pretty big. (and because Flexible Layout is enabled, Hype’s automatic optimization won’t resize them at all as they could grow to be any size). This is probably the best option to consider
Use crossfade transitions instead of instant transitions. If you use a short time, like .2s, it kind of creates a camera flash effect, which is interesting. Longer times means they won’t really be noticeable. You could also try push transitions.
Add the images to the first scene, but put them behind the title image or at a really low opacity. This will cause the browser to do a fair amount of the loading, so there will be a lot of the data cached for subsequent scenes. However I can’t really recommend this since it will eat up a lot of memory!
Also note that your images are set to Preload. While this is meant to help ensure there’s delays in showing the image (at least from the network traffic!), you do have a lot of images and data, so this could hold up showing the initial page, especially for folks on slower connections. So if you plan for this document to be online, you may want to consider structuring the document around what it would be if there was no preloading.