In some sections our codes are almost identical but the author hasn't published all the code.
Fortunately It would seem that my bug happens in a section of code that the author published and I compared my code with his and they are the same.
As all the geometry of my point grid looks correct, it's just that some triangles are drawn right handed and others left.
I am making the assumption that the other code is correct and hasn't overlooked two sided polygons.
This is the section of code (You will find similar code in the other authors code)