Fragment addToBackStack() and popBackStackImmediate() not working

Question

I am currently building an application for Android (14 <= SDK <= 21) by using one ActionBarActivity and more Fragments, such as ListFra

Answer 1

First of all, I wanted to say a big thank you to the highlighted [Nick]'s answer (Low reputation can't comment underneath), for helping me know there WAS actually something that didn't get mentioned in the Android Documentations.

Second, it's 2019 now, and after stumbling for a similar way in Androidx's Preferences, I couldn't find anything for a long time, until I was both checking this question and an official sample code in Kotlin, which this question led to a clue and the sample code's way actually was the solution in my case, works like a charm with a very tiny piece of overwriting, hope it helps as well for those who are looking for an official solution

@Override
public boolean onSupportNavigateUp() {

    if (getSupportFragmentManager().popBackStackImmediate()){
        return true;
    }

    return super.onSupportNavigateUp();
}

Aforementioned code in Java (Screenshot)

P.S. My first answer EVER on stacksoverflow, after more than of at least 5 years of using it ^^