It seems to work better than before but I need to give it more tests.

I got a similiar issue when I tried to do some thing on onReleased event of MouseArea. In my case I pressed mouse area and started doing my stuff.
But in between I lost the focus from mouse area (By some other action eg:- Alt + tab key pressed) and missed to get the onReleased event.
From that I understood that OnReleased called only if I pressed/dragged and released the mouse normally without any interference like focus change by other means. So I changed my code by using onPressedChanged instead of onReleased.

onReleased: { /// No guarantee to get invoked always when i released the mouse(unless it has focus)
}

onPressedChanged: {
if(pressed) {
/// Mouse is in pressed state.
}
else {
/// Mouse released. Either by user released the mouse button or by focus change to any other control.
/// Here it is ensured that release will executed.
}
}