QComboBox drop down is not visible on Windows11 in some situation

If a custom delegate is used with QTreeView which provides a QComboBox as editor, the combo box popup does not open. This works on Windows 10 with explicitly calling showPopup in an evenFilter but very strangely same code does not works with Windows11. 

This is the case when QTreeView is used in QGrapchicsView using QGraphicsProxyWidget.

Attached example can be used on windows 11 to reproduce.