Checkbox on Mac stays checked in the UI after setCheckState(Qt::Unchecked)

I have a simple QCheckBox in a QWidget.

After checking it with the mouse

checkbox->isChecked() returns true and the checkbox in the UI is checked

If I now use checkbox->setCheckState(Qt::Unchecked) 

now checkbox->isChecked() returns false.

So far as expected...

On Windows the checkbox in the UI is now unchecked 

But on Mac in the UI the checkbox is still checked, although checkbox->isChecked() still returns false. To uncheck it I now need to click 2 times on the checkbox control to uncheck , as if it was unchecked. (looks like the checkbox behaves normal, but shows a wrong state)

Only if the application is no longer active (focus on another app) the checkbox gets unchecked

I can reproduce this on 3 different Macs all with the actual OS Version (10.13.6)