Why doesn't startActivityForResult() lead to onActivityResult() execution?

Still trying to make my screen record app. I keep on working with MediaRecorder, as I was told some time ago, so I got stuck with another problem.

I just need to initialize a MediaProjection object to make my code work, that's what I do in onActivityResult(), as it's written in this guide:

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    if (requestCode == RECORD_REQUEST_CODE && resultCode == RESULT_OK) {
        mediaProjection = mediaProjectionManager.getMediaProjection(resultCode, data);
        screenRecorder.setMediaProject(mediaProjection);
    }
}

The setMediaProjection() looks like

public void setMediaProject(MediaProjection project) {
    mediaProjection = project;
}

, so it shouldnt't cause any trouble.

And that's how I try to call onActivityResult():

/* start transmission */
        if(screenRecorder.isRunning()) {
            screenRecorder.stopRecord();
        } else {
            Intent captureIntent = mediaProjectionManager.createScreenCaptureIntent();
            startActivityForResult(captureIntent, RECORD_REQUEST_CODE);
        }

The fun and crazy thing is that when I first launched the debug, it worked! After startActivityForResult() I got to onActivityResult() and initialized mediaProjection: my phone showed me a dialog window whether I allow to capture the screen or not, so I allowed that and got a special symbol (smth like screen with displayed waves) at my status bar.

But a few moments later I found an issue when stopping the record and restarted the debug session to trace it more exactly. After that onActivityResult() is just ignored: startActivityForResult() is called, the dialog window is shown, but after allowing the record onActivityResult() is completely skipped and mediaProjection is null. The restarting and re-installing the apk with the same code didn't fix anything.

Thank you very much for any suggestions.

There was a very simple solution. I just initialized the record service that put null into mediaRecorder's mediaProjection, so after that I was unable to re-initialize it. Putting intent which called onActivivtyResult() into activity's onCreate() before starting the service fixed that.