I have been using macOS Catalina since its release but today the Dock suddenly refuses to hide. In the preference pane, the
Automatically hide and show the Dock option is greyed out.
I have tried
killall Dock which hides the dock for 1 second, then it comes back.
macOS details OSX Catalina 10.15.5 (19F101) Mac book pro 16" 2019