Custom UMaterialExpression Node - works but fails Packaging

I managed to write an extended UMaterialExpression that actually worked as a custom node in the editor and all it did was take a Texture2D and check the pixels one by one for highest/lowest values on RGB and then throw that value out by abusing compiler’s Compiler->Add (just for testing purposes so I didn’t have to edit the engine itself) by adding the value i got + 0 together so that I would get the calculated value as output.

And it worked GREAT in the editor, however when we tried to package the project it failed.

FTexture2DMipMap* MyMipMap = &Texture->PlatformData->Mips[0];
FByteBulkData* RawImageData = &MyMipMap->BulkData;

The issue is here. For some reason DURING packaging it fails because it can’t access the mips (the base texture does have a setting of no mipmaps (which was the only way to get this to work in the first place in the editor.)

Any ideas how i could read the pixels from a texture in a different manner rather than from mips?

as a side note I also tried implementing it directly into the engine (so placed exactly the same way as all the other ones are with the same result.