Typo3 Backend Debugging (Extbase)

I try to debug some things from a backend module (ActionController / Repository classes) using
TYPO3CMSExtbaseUtilityDebuggerUtility::var_dump(). Unfortunately this has no effect. I remember that normally there was a panel in the backend showing the data, but in my case this doesn’t appear. I enabled the debug preset in the configuration. Does anyone have suggestions?

Thanks
Sebastian