Elements in the webpage is shown above / below one another based on their z-index.
So, in this case, it seems the sticky app has a higher z-index than your cart.
Follow these steps to fix it:
(1) Open the app > advanced tab > custom Javascript box:
document.querySelector('#cb-sticky').style.zIndex = "1";
(2) Open the app > advanced tab > custom CSS box:
#cb-sticky{
z-index: 1 !important;
}
(3) Save and test.