Is it .jpg?
What layer of the colours are the textures on? If they've shifted to a different colour layer then they'll forever remain white.
Applies to Blender DTS exporterEXPORTER: Translucent subtractiveTEXTURE: White is black, black is transparentEXPORTER: Translucent additiveTEXTURE: White is white, black is transparent