The walk or run toggle key toggles your slowest walk and the Change Combat Pace toggle key changes between combat pace and running. Seems like an easy fix by the player by changing his controls, but it actually inhibits intuitive movement.
The change combat pace key should change between slow walk and combat pace, while pressing the key bound to Walk or Run should put you into a run regardless of combat pace or slow walk.
The way it is now, the change combat pace toggle key changes between combat pace and run, so if you're slow walking, and you get shot and and want to run, pressing the change combat pace key, only switches between combat pace and run in the background, so you remain in a slow walk unless you press the walk or run key again as well; if in the background you are in combat pace, pressing the walk or run key will only move you out of slow walk and into combat pace, so if you want to run, you will also have to hit the change combat pace key as well.