Pick Block doesn't seem to work in Survival

I went into the setting of the Xbox One Minecraft Beta and set Pick Block to the left D-Pad. I've used this setting on survival on Xbox One since it came out and it's helped me tremendously with building so I wouldn't have to constantly go back into my inventory.

Now, for some reason, I just can't seem to get it to work. I have the control set, but pick block just isn't working.