The bug 
Recently, me and many others have had issues with changing out the default walk animation. This is because of a strange bug happening in studio. There are two movement animations in the default “Animate” script called: “Run” and “Walk”. These for some reason has to be set to different AnimationId’s or else your characters animations will break and you just float around everywhere. But When you test locally or just see your character on your screen it’s totally fine and everything works. But in the eyes of the server and the other players your just a floating T-pose man.
How to Replicate 
From what I have seen the most popular methods of changing the default walk animations is either copying the “Animate” script over to StarterCharacterScripts and changing the animationId’s inside the copy or writing a server script like this:
But either of these methods will break if both the walk and the run value gets set to the same Id. It will turn out like this.
The Fix 
Ofcourse I still think this should be adressed and looked at by the devs since this has caused alot of confusion to new scripters just starting out that encounters this bug. But before that day comes here is how you can prevent this from happening. You just gotta make sure the “Run” and “Walk” AnimationId’s are different, even if you set one of them to 0 it will remain functional.
Some Other Tips for chagning the default walk animation 
- The “Run” Animation value is what roblox follows in default state. (Not the “Walk” Animation)
- The animationId’s written inside the “Animate” script dosent matter it’s the values parented to the script that controlls the animation.
- Dont have duplicated AnimationId’s in any of the Animations
Repro File
Repro file.rbxl (15.0 KB)