I've got one of those Macs with a TouchBar and even when my touchbar is showing F-keys, F4 sometimes just doesn't send anything (to any program). There's no way

I've got one of those Macs with a TouchBar and even when my touchbar is showing F-keys, F4 sometimes just doesn't send anything (to any program). There's no way that my case has anything to do with the settings you are talking about.