I’m not super familiar with how sounds work, are you sure the sound would be playing if the code doesn’t call :Play on it anywhere?
Do sounds automatically detect changes to their SoundId property and change the sound they’re playing or do they need to have Play called on them again to update that?
Are you sure that footsteps is a sound? If it’s not, the code wouldn’t work with no warning. (It might be better practice to throw a warning when that happens, or wrap the loop in a task.spawn and throw an error.)
(Just a random note, Realism has a really good footsteps sound creator with sounds for all sorts of materials that works really well.)