Instant pot steaming function varying results

I mainly use my 6qt instant pot to steam vegetables, those are generally things like mushrooms, broccoli, carrots, onions, zucchini and bell pepper.

I usually put 240 ml of cold water into the Instant pot, place the veggies into the steamer basket and choose the steam option for 2 minutes on high pressure with manual release.

This works perfectly 60% of the time, however sometimes the pressure is built too fast and the vegetables are mostly raw after the 2 minutes when the instant pot built enough pressure.

I tried different amount of water, different temperatures of the water and nothing gave me consistent results.

What could I be doing wrong? This is really frustrating