In STM32CubeMX / STM32CubeIDE100, In the Clock Configuration page, the pull-downs disappear when trying to alter the selection, making it impossible to change them.
This is not with all boxes, but with PLL2 and PLL3 pull-down boxes.
UPDATE:
I found a work-around: Click on the box, don't move your mouse to the selections, but press the up and down cursor keys and then Enter.
