Managed to find the issue in Xnormal :) It seems the "edge padding" setting was set to high which caused the brick color to "drown" the grout color. Also, my grout texture consisted of 2 polygroups which actually splitted the mesh in 2 seperate ones. I collapsed them together and reloaded them and voila: Really thanks a…
So I tried extending the bricks but I am encountering the current problem: I realise the edge bricks distances need to be exactly the same but the problem is that these 2 bricks have different dimensions.
I don't really know about Max, but in xNormal you can bake out vertex colours for the mask, or in your case if you are loading up 2 high poly models, you can use the "Bake Base Colors" map in xNormal which will randomly assign each different mesh a colour. On another note, looking at your high poly, you may run into issues…