A Flaps only case.
According to good old FCOM 3.01.20 p9:
Stall speed when clean and 61.5 ton is about 152 kt.
With conf 1+F stall speed is about 118 kt.
With conf 2, stall speed is about 111 kt
Could we say that stall speed for no slats/flaps 1 should lie somewhere between 118kt and 152 kt? Or that stall speed for no slats/flaps 2 should lie somewhere between 152 kt and 111 kt?
Nope! Because this is a flaps only case. Extending flaps only (no slats) means a reduced stall AoA. Remember the curve, with higher CLmax but smaller stall AoA.
For the same attitude, it could happen that you have a "good" AoA flying clean at 190 kt (38 kt margin or approx 20%) but are too close to stall AoA at the same speed when flaps 2 are deployed.
That would explain what happened to you in the sim.