I’m okay generally okay with MTB mechs. but setting up the GRX 400 front mech. has been a nightmare (partly because Trim was something new & I kept thinking that, somehow, the adjustment was out of wack when in reality I should have been in a different mech. position).
Something that I have discovered is that I was tensioning the cable before securing it by pulling it through & away from the mech which (unless the cable was dead straight) could result in the top part of the mech. (where the cable secures) being moved forward & throwing things out. Wrapping the cable through its full routing and pulling from the back has helped.
As it stands though I still can’t eliminate all rubbing at the extremes in the big ring (the small ring is fine). With my 3×10 mountain bike mech. it’s all a lot easier.