Migrating Streaming Data to 4.15 Problem

So we have recently migrated our material information using BuildMaterialTextureStreamingData in each level.

We are seeing some weird things happening. Some of the parent materials looked to switch. This is an easy fix. The other issue we are seeing is some materials are not rendering/compiling in cooked builds. (Gray Texture)

Are we using BuildMaterialTextureStreamingData command correctly ? Do we need to save all materials again to fix weird issues. Any information at all would be great.