Changing to a non projected plug was going to be one of my wild assed guesses. If by chance if it changed the way the plugs looked I wouldn’t have a real clue as to why, other than other wild assed guesses.
And that guess would be that you are moving the very tip of the plug out of an area in the chamber that has a vortex swirling around.
Of course, that is blatant speculation at best.