$ defaults write com.apple.dock appswitcher-all-displays -bool true
$ killall Dock
Copied from https://apple.stackexchange.com/a/419822/459171 as backup.
$ defaults write com.apple.dock appswitcher-all-displays -bool true
$ killall Dock
Copied from https://apple.stackexchange.com/a/419822/459171 as backup.