When I say nudge the faders, I mean you can move them back and forth to the exact same position and suddenly the gain will be played back correctly. I don’t mean changing the track volume. Try it by opening a project with all faders raised, move them down and back up and voilà, gain is corrected.
It also fixes it after following your steps of adjusting gain then opening waveform editor, where gain is ignored after exiting. Any movement of fader will revert to correct gain