Hello, @Wade Yang,
Actually, In the mobile menu, there is an option “More Toggle” only this one has the option to set the menu in it. See the image: https://postimg.cc/SnFjGLk0 so you have to rename the “More Toggle” to “Mobile Menu” and then assign your UBER Menu to this as I show you in the image above. This is the only possible way.
Regards 8Themes Team.