Safari 12 Mac: does IncludeInternalDebugMenu 1 still work?

Hello,

I am trying to enable the "Debug" menu in Safari 12.0.1 on Mojave 10.14.1, the command should be:

defaults write com.apple.Safari IncludeInternalDebugMenu 1

However, nothing happens.

For reference a "Debug" menu should appear in Safari in the menu bar as described for example in this blog: https://www.igeeksblog.com/how-to-enable-debug-menu-in-safari-on-mac/

Does this command still work on Safari 12? Is there a new way to show the Debug menu?

Thank you