Open QComboBox Item list on maximized QDialog with QComboBox after layout switch - background application visible on split view

Preconditions:

Application includes maximized QDialog with QComboBox.
Application is on portrait mode. Split view is open with qwerty keyboard.

Test steps:
1. Switch the layout from portrait to landscape.
2. Tap the small arrow button on QComboBox.

Expected result:
List of items is displayed (Item 0, Item 1 etc.) with Select and Cancel buttons.

Actual result:
List of items is displayed (Item 0, Item 1 etc.) with Select and Cancel buttons.
Part of application grid is visible between the Items list and control pane (select and cancel buttons) area.