N-channel MOSFET not fully OFF
If the "MCU" signal is going up to 3.3V then Q1 should be fully saturated, and it should pull its collector down to 0.2V or so.  If it's only going down to 0.6V then you have a defective transistor in there, you've put it in backwards (emitter where the collector should be, collector where the emitter should be), or your MCU doesn't have enough drive to bring the "MCU" line up to its rail (it should be almost at the rail; it certainly should be within 200mV, i.e. 3.1V for a 3.3V rail, 4.8V for a 5V rail).

I suspect you just plugged Q1 in backwards.  Double-check your pinout.  Then measure the voltage at MCU.