Do a 2-finger drag on touch pad. Don't flick ie. make sure to stop the movement before releasing. When you lift your fingers, Flickable does not emit movementEnded() and the value of the moving property stays true.
If you have for example a ScrollIndicator from QQC2 attached to the Flickable, the indicator does not hide since it thinks the content is moving.
Reproducible with the latest released pre-built versions of Qt 5.6 and Qt 5.7, and the latest qt5 5.7 branch.