Just my 2 cents here: perhaps it is not the right choice to use [-5,5] as the approximation interval since it contains x=0, where 1/x is not defined.
Plus, the fourth argument of EvalDivide is the polynomial degree, which should be set to a larger value, otherwise you are just creating a line.
I refer you to: https://openfhe.discourse.group/t/how-to-evaluate-approximate-1-x-function-with-high-precision/