Pure ANC won't turn on or off

I’ve a pair of Beats by Dre Studio 3 and they have Pure ANC.

If I want to switch it on I’ve to double click the power button, same thing goes for turning them off. Problem is that it doesn’t work and it seem to be pretty random… yesterday it was always on and the double click didn’t work to turn them off, instead today when I was used them I realized the Pure ANC was disabled and I tried to turn it on the whole day without any luck.

Are they just broken? Do they work fine for you? I paid them 350 dollars and have them from 2 days so I’d like to understand if it’s just my problem or I didn’t understand how they actually work.