Chainging Waist C0 Effects Running Animation

Hello everyone,

I am currently working on a script that will move the characters torso according to where your mouse is in the world space. The problem is, is whenever I change the C0 of the waist, it makes the character runs with its arms bent for some reason.

Here is the script:

local player = game.Players.LocalPlayer
local mouse = player:GetMouse()
local character = player.Character or player.CharacterAdded:Wait()
local hrp = character:FindFirstChild("HumanoidRootPart") or character:WaitForChild("HumanoidRootPart")
local waist = character:FindFirstChild("UpperTorso"):FindFirstChild("Waist")
local o = waist.C0

game:GetService('RunService').RenderStepped:Connect(function()
	
	waist.C0 = o * CFrame.Angles(math.acos((hrp.Position.Y-mouse.Hit.Position.Y)/(hrp.Position - mouse.Hit.Position).Magnitude) - math.rad(90), 0, 0)
	
end)

Here is what it’s doing to the run animation:
https://i.gyazo.com/8a708e3ab7d40bc6a5e85dd42d0f2be5.mp4

If you know why this error is occuring, then please let me know why.
thanks,