Even without the plastic insert, it is held in place and functions normally (until the rod is unscrewed.)
Can you explain that please?
We're assuming the lug nut is of traditional design. By what's being said here we assume there could/should be a channel cast in the metal section which would hold the lug nut in place during tuning/tension, or is the plastic piece part of this function?
What we're getting is w/o the plastic piece the lug nut is held in place, but also hearing if there's no tension/rod and plastic piece not in place, the lug nut would fall out.