Incorrect render \( and \)

1) "Integral \[\int_{a}^{b} x^2 \,dx\] inside text" is rendered
2) "\[\int_{a}^{b} x^2 \,dx\]" is rendered
3) "Integral \(\int_{a}^{b} x^2 \,dx\) inside text" isn't rendered
4) "\(\int_{a}^{b} x^2 \,dx\)" isn't rendered