Font change is applied on the second popup appearing.

You should look at item "1".

Open popup,
At one moment, it looks with line in the bottom of "1".
Open popup again.
"1" is without line in the bottom - font has changed.

Affected tests:
ControlsAutomatedTestSuite/javafx/scene/control/test/choicebox/ChoiceTest/show
ControlsAutomatedTestSuite/javafx/scene/control/test/choicebox/ChoiceTest/showAPI