This diagnosis is only relevant to UberMenu 2, not UberMenu 3
The slide and fade effects of the submenu are accomplished with jQuery. They will not appear with jQuery Enhancements disabled.
HoverIntent & Click triggers
The top level menu item triggers are all powered by jQuery. If you disable jQuery Enhancements, the submenu will appear immediately upon hover – Click and HoverIntent triggers will have no effect.
Responsive Menu Toggle Button
The click event on the Responsive Menu Toggle button is controlled with jQuery. You need to enable jQuery Enhancements for Responsive sites.
Re-enable jQuery Enhancements in the UberMenu Control Panel > Basic Configuration > jQuery Animations & Auto-positioning > jQuery Enhanced