The least desirable stall characteristic any jet can have is to pitch-up when it stalls, the reason being that the wing can blank out the horizontal stabilizer causing a loss of pitch control and the ability to get the nose down to fly out of the stall.
That is a common explanation. But there is a better one.
Flaps settings are not only alter chambers it alter as well average incidence angle.
Assume the fuselage itself acts as a wing.
That can lead to situations in which the wing produce less lift than the wing.
the scenario is at low IAS and at low flap settings the fuselage can produce more lift than the elevator can counteract.Supercritical wings are knows (esp. the earliest) for poor lift creation, what increase the effects. That lead into a not controllable but stable situation, in that the wing itself isn't stalled, called superstall. During landing the flaps are set, running the wing at notable higher angle of attack than the fuselage, so that the fuselage can't produce lift.
I used x-plane for investigation the flying wing and lather on together with a fuselage formed from wing shape. I discovered severe problems with liftoff and also in diving, when the fuselage produce lift (in that case-negative lift).
That isn't a suspect into the case, just a comment into the general relation. If more discussion about this, admins split into a own tread.