Change the breakpoint to display the burger menu on the desktop screen or how to return the menu format to be the same as version 8 of Mendix?

I'm working on a client that made all of its layouts based on the Atlas UI of Mendix 8. We migrated to version 9 recently but the menu is behaving strangely and quite differently to display the second level items. I would like to know if it is possible to achieve the same behavior of the menu in version 9. If not, how do I change the breakpoint so that the hamburger menu appears in the desktop version?      EDIT:  The menu is also behaving strangely on the ATLAS UI website ( - the correct behavior came back when I shrunk the screen to force the media query and went back to size original. So I think  we have a bug in Atlas UI.
1 answers

have you upgrade to atlas core ?