Due to some changes in the rc updates fo Joomla4, the way to setup your menu has changed, or rather, you need to take something into consideration.

When publishing the menu module, you have to use a certain setting for the menu to work as desired.

  1. First publish the menu module in the menu position, and select the menu of choice
  2. Publish it on all pages you want it to show, or simply all pages
  3. Then you have to set the following: choose the layout option to be a Collapsible Dropdown

So, now you are all set to use the menu as shown on this website.