Automatische Entwicklung

Are all sliders at zero? If not, them maybe you have selected a camera default that already uses 'Auto'. If 'Auto' has been applied, and you did not manually change any sliders again, then you cannot apply 'Auto' again (because it would not make sense).

The translation to English says "I can no longer click..." but I assume you mean that clicking on Auto doesn't do anything. Please try resetting your preference file. https://www.lightroomqueen.com/how-do-i-reset-lightrooms-preferences/