ComboBox stops working on live preview after "Fucus" is set to true

I'm using Windows 11.

At first, ComboBox displayed the value candidates when clicked.

However, once I changed the "Focus" to true in the property tab, it stopped showing them even when clicked.

For it to work, I had to close the live preview once and re-started it.

I attached the project, "Sandbox3.7z".