ComboBox GotFocus and dropping down

I am finally looking at an unexpected behavior with my Combobox and GotFocus… On my PC I click on the box and it drops down, but on my Mac it must cycle through before it drops down. Is this expected from having GotFocus? Is there an alternative?
I use GotFocus to clear out stuff from the previous use

What “cycle through” mean? Sorry, I have no experience with Combobox.

Sorry, but I miswrote. I click on the first box’s DropDown arrow, and it drops down and immediately disappears.

On the second box, it stays down.
The first box has maybe a hundred rows in it, while the second has maybe six.

I just deleted GotFocus and it still disappears.

My font selecting box has a similar large amount of rows but not the same behavior.

Can you share some code/sample?

I am not sure what code to share since nothing happens until a selection is made.
There is also no database attached to the box.

i cannot show an example of what happens because it disappears extremely fast. It is faster I imagine than double clicking on the drop-down arrow.