Old School Animation Pack Doesn't Work With Custom Animations?

I’ve been creating a very simple custom animation pack for my game.

For the script, I’ve used the script provided by the Developer Hub, so I know that the script can’t be a problem.

More specifically what script I used
local Players = game:GetService("Players")

local function onCharacterAdded(character)
	local humanoid = character:WaitForChild("Humanoid")

	for _, playingTracks in pairs(humanoid:GetPlayingAnimationTracks()) do

	local animateScript = character:WaitForChild("Animate")
	animateScript.run.RunAnim.AnimationId = "rbxassetid://6300166393"        -- Run
	animateScript.walk.WalkAnim.AnimationId = "rbxassetid://6300166393"      -- Walk

local function onPlayerAdded(player)


If I use the “Old School” walk/run animations, I get this output:

18:56:25.783 - RunAnim is not a valid member of StringValue "TheSuzerain.Animate.run"
18:56:25.784 - Stack Begin
18:56:25.785 - Script 'ServerScriptService.Script', Line 11 - function onCharacterAdded
18:56:25.786 - Stack End

When I use any other animations from other packs, it works just fine. If I change only the walk/run animation to something from another pack, it works just fine.

Video of me using Old School

As you can see, I get the error and it stays with the Old School animation.

Video of me using any other pack

Here it works, while I haven’t changed the script in any way, only my animations.

I’m pretty sure this is a bug, but I want to clarify before I make assumptions.

This would be better in #help-and-feedback:scripting-support rather than here.