THIS BOX IS FOUND IN THE MATERIAL EDITOR

This is a common mistake when using materials across packages. If you are using a material across packages make sure the flag that you need checked on, is checked on for the type of object you would like to use the material on. Then re save the package. this is a common mistake that solves textures not showing up in the build.
If the material was created and used with a static mesh it will only work for static meshes once saved.
If the same material is used on a skeletal mesh in a different package it will work in the editor.
BUT WILL NOT WORK IN THE BUILD
If the material was created and used with a static mesh it will only work for static meshes once saved.
If the same material is used on a skeletal mesh in a different package it will work in the editor.
BUT WILL NOT WORK IN THE BUILD
Check to make sure the proper flags are on for cross package usage.