No function with function-keys when setting it to 'use as standard function keys'

Hello, I have a problem regarding the function keys on my MacBook Air.

I like the setting to have them being normal function keys to use them in applications and, with the 'fn' Button held down, being the 'adjustment keys' like volume up or down.

(System Preferences -> Keyboard -> Keyboard: 'Use F1, F2, etc. keys as standard function keys - When this option is selected, press the fn key to use the special features printed on each key.)

Almost every key works like that, the

• Volume Keys
• Screen Brightness
• Mission Control
• Music Controls

do work when pressing the fn key and one of them.

But there are some, that don't work when having the setting enabled, so pressing 'fn' and them results into nothing. These key are

• Spotlight
• Speech to text
• Do not Disturb

So, I need to get this fixed. I want the buttons that currently don't work to work when I press 'fn' and one of them, just like volume etc. do.

Just to be clear, when the setting is off, they do work, only when it's on they don't react.

Or is this some kind of 'design decision' because they are the 'new' keys that were just added? Maybe it's also because of some regional problem (I have a German Keyboard-Layout).

I'd be very happy for any help!