I don't know if it's the cause of everything, but you should not round intermediate results.

Please format your code or it's unusable, see there: https://docs.codewars.com/training/troubleshooting/#post-discourse

Your algorithm is correct but your function is modifying the input arrays in place which is bad practice. As long as a function causes side effects when it is invoked, its behavior is undefined which means that you cannot guarantee that your function will produce consistent results every time. Consider computing the sums and cubes of the numbers as you are summing up the results instead of reassigning each value in the array before performing the summation, cheers :)