Icon does not appear in iOS on iPhone 6 +

[Sannyasin Brahmanathaswami]

We have an app in development, Yesterday I prepared all the icons and splash screens. The standalone builder was happy with the size of everyone of them.  I run a build and

1) the logo does not appear on my iPhone 6 Plus:  even though we have a good png at 180 X 180

it is somehow not being applied.

2) splash screen does show

Any clues?  on the logo? is this a standalone builder failure or a file naming convention I am missing?

What is the "Prerendered Icon" check box used for?

BR