It appears you're referring to drop down element, please use Navigation collapsed or navigation layer elements instead of that one. The dropdown element works similar to inline menu element and both are meant for desktop for hover functionality. The only difference is, the dropdown element has no top-level or parent menu.
And due to the nature of mobile devices, I recommend deactivating the sticky bar for mobile. It's intentionally inactive for standard X header, but since it's a custom header from Pro then it has to manually applied. Example, the issue that may arise is having a tall menu that bleeds outside the mobile screen and since it's sticky, it would follow along as you scroll which means, the area that bleeds out will never be accessible unless sticky option is deactivate.