All fill/hatch patterns are locked to the main category of Detail Items and export by default to (I believe) either A or G-Detl-Genf. The single cad layer can only have one color associated with it. That color determines whether the pattern will be halftone or black line. This is a problem, at least for me, since I use both halftone and black line patterns.
Exporting with overrides by entity or with new layers create their own, additional problems.
I have posted 3 drawings to show the differences.
LTNG 3 override by entity.dwg