Cannot type into field to "Simulate Keystroke"

If I try to create a new action by invoking the "Interface Control" menu and select the "Type a KeyStroke" menuItem, I cannot type into that field from the keyboard at all. I can select any of the options from the pullDown menu, like "Tab" or the list of functionKeys.

Any help appreciated . KM 9.0.6. Mac OS 10.15.7.

Craig