Your FET is an N-channel device, and so it requires Vg to be higher than Vs to turn on. And that never happens, if Vs is 3.6V and Vg is 1.5V so Vgs is always negative and FET is always off.

The FET also has an intrinsic diode as drawn, so basically the IPS node on drain will always get about 0.7V less than source voltage.

So first of all you need a P-channel FET, with Source to 3.6V and Drain to IPS. But then you need to pull the gate down to 0V to turn it on, and leave at 3.6V to turn off. You need a transistor to take in the 1.5V signal and invert it and level shift to 0V/3.6V signal.

Or you could buy a load switch that has an active high enable input and has a logic level threshold so that 1.5V can be used as the enable.

Your FET is an N-channel device, and so it requires Vg to be higher than Vs to turn on. And that never happens, if Vs is 3.6V and Vg is 1.5V so Vgs is always negative and FET is always off.

I also don't see how it could have worked with a 2N2222 transistor either.

The FET also has an intrinsic diode as drawn, so basically the IPS node on drain will always get about 0.7V less than source voltage.

So first of all you need a P-channel FET, with Source to 3.6V and Drain to IPS. But then you need to pull the gate down to 0V to turn it on, and leave at 3.6V to turn off. You need a transistor to take in the 1.5V signal and invert it and level shift to 0V/3.6V signal.

Or you could buy a load switch that has an active high enable input and has a logic level threshold so that 1.5V can be used as the enable.