I've upgraded Active shield (Quen) to level 3 and have it in the list to the right. But it doesn't appear to do anything during combat. I hold it in and I see the shield, but the instant I let go of Q the shield explodes. Is it really supposed to work like that? In that case we have to keep holding it in all the time, which makes it impossible to move properly given that Q is for the sign and movement is WASD.

When selecting it, I hoped it would be just like the normal Q, so that when I've selected it, it will be in effect until it is destroyed. Haven't found much useful info by searching elsewhere, so please explain how this thing is actually supposed to work. Cause right now it feels like three totally wasted points :-/

Yes. It's called 'Active Shield', which means it has to be actively sustained. Letting go with the shield exploding is also a feature.

Thanks. Makes it less useful than I thought it would be, but I've still got some use out of it in crowded fights.