Texturing not working properly

At the moment I'm using DAZ Hexagon 2.5.1 on Mac to model some props, and importing them into Unity to do texturing using GameDraw, since the Hexagon UV unwrapper isn't that great. GameDraw works like a charm and everything's fine UNTIL I close Unity. When I open up my project again, on all props I've textured using GameDraw, the entire texture is shown on each face, giving complex props the look of having one single colour.

I'm wondering if anyone could let me know if they've had the same experience. Chances are I'm doing something wrong. I'm hoping it's not a GameDraw bug.