I looked into this and I think I figured out what's happening - you have a gamepad plugged in and Analog Input turned on, but you're using the keyboard to play? For some reason this makes directional inputs always read as zero so there's probably a priority issue (so the logic uses the blank inputs from the gamepad even though it knows you're in keyboard mode).
You can solve this by opening the options menu and turning off Analog Inputs (or unplugging the gamepad), I'll try to get a fix for this done ASAP.