QComboxBox list stops popping up

QComboBoxes randomly stop being able to have selections made because clicking on the widget no longer pops up the list to select from.  This is in code that has worked for years so I suspect something has changed under the hood.  I get error messages such as the following from the QComboBox when I click on it.

Warning : QWindowsWindow::setGeometry: Unable to set geometry 131x122+1204+1219 (frame: 131x122+1204+1219) on QWidgetWindow/"QComboBoxPrivateContainerClassWindow" on "HP ALL-in-One". Resulting geometry: 131x122+2226+1852 (frame: 131x122+2226+1852) margins: 0, 0, 0, 0 minimum size: 2x2 MINMAXINFO(maxSize=POINT(x=0, y=0), maxpos=POINT(x=0, y=0), maxtrack=POINT(x=0, y=0), mintrack=POINT(x=2, y=2)))

I have multiple combo boxes in my app.   Any one of them seems to sometimes inexplicably stop working.  I exit the app and restart and it works again. The combo boxes typically have 4 or 5 items in them, so not large.

I'm not giving you much to go on, I know.  But if you get other reports like this, then you might conclude that there is a real problem here.