Hello Greg,
For the "Standard grating", the "Variable grating, polygonal", the "Variable grating, rectangular", the grating orientation is taken from the UCS.
For the "Grating at polyline" orientation, your comment is correct (= its orientation is not taken from the UCS) => our R&D team is currently analysing the issue.
For info, you can rotate a polygonal grating by selecting its orientation symbol and use the AutoCAD Rotate command (but it rotates the whole grating element).
Regards
Philippe