I can't pick up items.

I created a character. Stabbed the zombie that drops first weapon. When I go to left click to pick up the item, it doesn't get picked up. I'm unable to pick up items. Made new characters of other classes to see if they can pick items up, no dice across the board. I've tried WASD/Keyboard & Mouse, even changed the 'item pick up' hotkey. Is there a secret to pick up items in this game?