Torsos and Root Parts do not work when setting a Collision Group

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#1

Hello!
I was using physics service to set all of the characters parts to a collision group. it worked for every part except humanoid root part, and torsos. Please Help!

script:

for i, v in pairs(char:GetChildren()) do
			if v:IsA("BasePart") then
				physics:SetPartCollisionGroup(v, "aCharacters")
			end
		end