Is Multisim simulating right?
I have tried this with higher voltages and I think, that multisim seems to work correctly when you are not exceeding devices maximum ratings. If you put 100V at the input of op-amp powered from 30V - do not expect any correct results.

In real life op-amp with input voltage above maximum from datasheet would blow up - I dont remember internal structure of LM324, but there are probably ESD protection diodes. They blow up first in that scenario.

My conclusion is - check voltages at input and output pins and make sure they not exceed maximum ratings :)

Also, notice that in your circuit you have voltage dividers at the op-amp inputs and they divide your input voltage by 120ohm/(100ohm+120ohm) = ~0.54.

V2 voltage is divided by R2 and R2, so you have ~21,818V at noninverting input

V1 voltage is divided by R1 and R4, so yoy have ~17,454V at inverting input