I'm not sure what I did exactly, but I was trying to replace the battery in the flashlight, and somehow I've disabled by ability to move forwards, even after reloading my save
Edit 1: To be clear: I can still move left, right, and backwards, and all directions still work within the coordinates panel.
Edit 2: After more gameplay, this is now a critical bug, as I cannot climb the radio tower ladder to repair it.
Edit 3: After a full game restart did not resolve the bug, I did a hard-reset of my keybindings, which *did* fix it. The strangest part is that I had never changed a keybinding, so that shouldn't have had an effect.