Settings won't allow entry of system-wide hotkey

Enpass 6.0.4 won't allow me to enter a system-wide hotkey in the General settings.  The box doesn't allow an entry.  This was true in the 5.x version I had installed previously.  I can add the hotkey in the Firefox browser extension, which works fine.  But if I invoke an application that runs independently of the browser, I cannot use a hotkey to call up a password.