See the attached demo. When you tap the button on a touchscreen, it fires the pressed signal (as demonstrated in the console output), but never gets released (no onCanceled, onReleased). I believe any touch control, even scrolling in flickables etc. gets cocked up the same way.

Also note that without the

ui->quickView->setAttribute(Qt::WA_AcceptTouchEvents);

the touch does not work at all, even when I specify

QCoreApplication::setAttribute(Qt::AA_SynthesizeMouseForUnhandledTouchEvents);

Also tested using TapHandler for the root Item instead of MouseArea, same problem.