QDrag on QGraphicsScene do not invokes dragLeaveEvent for QGraphicsProxyWidget

I have QGraphicsScene that shows QWidget(s) via QGraphicsProxyWidget.
Widgets can exchange data through D&D. Widget produces QDrag item according to docs.

When QDrag object leaves area of QGraphicsProxyWidget I expect to receive dragLeaveEvent() for the particular proxy widget. But it happens not always.

IF the scene ACCEPTS event in the dragMoveEvent() outside the area of proxy then dragLeaveEvent() DO NOT INVOKES in the proxy.

IF the scene DO NOT ACCEPT event in the dragMoveEvent() outside the area of proxy then dragLeaveEvent() INVOKES.

Pseudo graphic:

A B C

A - the pixel inside proxy
B - the border of proxy
C - the scene area

I drag item from A to C and expect for dragLeaveEvent() in the proxy. But if QDrag is 'accepted' in points A and in the point C then no event. If QDrag is 'accepted' in A and 'rejected' in C dragLeaveEvent() happens in the proxy.

Is this expected behaviour? As for me dragLeaveEvent() should be invoked in both cases.

In the attached simple example to confirm the issue need to change flag
bool acceptOnBlank
if true - the event handler

void dragLeaveEvent( QGraphicsSceneDragDropEvent* /event/ ) override

will never be invoked.

Attached file can be used in the 'Dialog Window' project of QtCreator