Switching inbetween items VIA hotbar remains difficult throughout development. Many cases has caused my characters death by being unable to switch from a benign object to a weapon VIA hotbar.

Example: Have canteen in hand (not drinking), see a zombie or player acting hostile towards me, and decide to switch to my weapon in my hotbar. I press the assigned number button and nothing happens. Press it again, sometimes it will switch, many times I have to press the button several times.