I finally figured it out. I have a tween of length 0, and I was setting its progress to 0. I expect setting progress to 0 to jump to the START of the animation. instead it was jumping to the END of the animation.
See the Pen WrBmEa by dax006 (@dax006) on CodePen
My apologies for the confusing question, I was trying to solve three separate problems in one question. You guys pointing out the known bug made me turn my tweenMax's into tweenLites, and then the other problem became clear. So I couldn't have solved it without you, thank you!
dax006's post in progress() is triggering onComplete handler? was marked as the answer