Why does Isreal function give wrong answer after using collect function

In the code below, the second function isreal gives wrong answer after using collect function.

clear all;
close all;
clc;

syms w real;

m=w^3-1i*w^2+2*w-1i;

mre=real(m)
isreal(mre)

mrecol=collect(real(m),w)

isreal(mrecol)

Answer 1

[Walter Roberson]

There is no isreal() function for sym specifically, so the result of both isreal() calls is undefined. But double check class(mre) and class(mrecol)