F16-F19 cannot be setup as plain FKeys in media mode.

I want F16-19 to work as regular function keys in media mode.

I can do this for F1-F12, by setting them as keyboard shortcut to themselves (e.g. F1 maps to keyboard shortcut F1).

But this does not work for F16-F19. When trying to record the keyboard shortcut, F16-F19 are not registered.