https://responsively.app/ is a must have tool for testing websites on multiple devices.
The instant preview mode allows you to preview all target screens in a single window side-by-side and you can choose a range of devices to use. It’s quick and efficient and can help reduce development time.
A common problem for the Max Mega Menu when there is an abundance of links and a fixed menu with minimum scroll available. MMM have posted 2 fixes here: https://www.megamenu.com/documentation/fixed-height-mega-sub-menu/ but if that doesn’t solve the issue you can try the modified version that worked for us:
@media only screen and (min-width: 992px) {
#mega-menu-wrap-primary #mega-menu-primary > li.mega-menu-flyout ul.mega-sub-menu li.mega-menu-item ul.mega-sub-menu {
overflow-x: hidden;
height: 200px;
overflow-y: scroll;
}
}