Why is my for loop not removing all of the items it should be in a table?

local Reg = MakeRegion(mouse.Target.Position)
	local Parts = workspace:FindPartsInRegion3(Reg,game.Players,math.huge)
	for i,v in pairs (Parts) do
		if mode == "ignoring" then
			if v.Color == ignoreColor then
				table.remove(Parts,i)
			end
		elseif mode == "target" then
			if v.Color ~= targetColor then
				table.remove(Parts,i)
			end
		end
	end

So the snippet of code above is supposed to remove all parts in the table that aren’t the color of targetColor when it is enabled, or are the color of ignoreColor when it is enabled. But for reasons I don't understand, when I print the length of the table at the end, it has only removed half and then stopped. Does anyone know why this is and what I could do about it?