if for some reason your menu's or other navigation elements disappear on a (double) click, this could be a bootstrap issue. In the template folder inside the js folder resided a boostrap.js file that needs to be modified. We have not done this in an update, because it is not happening on all sites. 

it is inside the dropdown.js section:

mark out the selected element. 

Screenshot 2019-05-08 08.24.59.jpg