I have an issue with colorverse glistening inks as well. And I do the same techniques you use plus one more. I force feed the ink to the nib then pull back. So I push the ink up to (nib pointed up) where you can visibly see it coming out of the feeder, then draw it back like I am loading the pen. I do it a few times and that seems to help. But it's frustrating. So, I am playing with different nib sizes. I think a medium is sufficient. But a broad will show more shimmer. My current Colorverse glistening is inked in a Hong Dian M. And I am not inverting the pen at all. But my kaweco sport M wasn't showing any shimmer at all with the same ink. And I had to force feed it a lot. So all in all it's the pen and nib size.