Shortcuts app has to run to use keyboard shortcuts
As other people already noticed on mac osx (in my case 15.6) shortcuts created with the shortcuts app and configured as keyboard shortcuts only work when the shortcuts app is running. (shortcut app shortcut keys only work when… - Apple Community).
I suggest configuring the shortcut app to start when logging in (shortcut app shortcut keys only work when… - Apple Community), the window can even be closed (command+W) and the keyboard shortcuts keep working.
This is no question, but to document the answer I would have wanted for previous questions.
MacBook Pro 13″