After playing with a few animations, I wanted to make some edits to them, and try converting some existing gifs into boot animations.

I found that when editing the series of images, if I pulled few out. edited them, and put then back into the Bootanimation.zip those particular frames did not play. And if I replaced all of the images, the phone wouldn't even boot.

After incorrectly assuming it was the image format, and size, and bit depth, the following column in 7 Zip tipped me off.

Ensuring the files were not compressed when added them back into the Zip worked. The zip only functioned as a container for the images, the compression should be done at the image level.