Some Pen / Ink combinations just dones't work.
I’m mostly a one ink in all of my pens kind of person. But I have slowly been accepting that some of my pens just don’t work with all inks. Like my two Pilot pens in rotation (Metal falcon and Vanashing point) aren’t the best unless the ink is really good lubricated. So I have more or less given up using them with anyhting but Iro inks.
While all my rest have good enough flow through the feed to handle most inks.