Here's a theory. Could the difference between an agouti and a self harlequin, be that the agouti has nose lacing(which agoutis do) and a self doesn't(which they don't have)
I have held does in position, by just stroking the head, to lifting the rear end, if they are reluctant but the vulva appears ready.My success rate is the same as no hands breeding. Sometimes after the first help, they seem to get it next time.
I have been breeding rabbits for 20 years(mostly Holland lops) and I would say 95% of my litters are delivered on day 31. I am surprised if they don't.