Unexpected results from voltage mulitplier
What is not in your simulation is the 10 Mohm impedance of your multimeter.

But 10 Mohm is quite a high resistance, so is it relevant?

Calculate the impedance of a 2.2 nF capacitor at 60 Hz and notice how it is about 1.2 Mohm, that's quite relevant compared to 10 Mohm. Also the capacitors are more or less in series.