Mac touchbar does not change when xdebug debugger is active

I have a Mid-2018 MacBook Pro with touch bar. I'm running a web server with apache / php-fpm in a docker container. When I'm debugging a request via browser, the debugger pane opens automatically and execution stops at my breakpoint. I thought the touch bar should automatically change to display the buttons defined in "Preferences > Appearance > Menus and Toolbars > Touch Bar > Debugger". That does not happen, the default buttons remain visible. How come?