The icon that looks like a filter or funnel takes you to the section that allows you to use the Filter feature.
By default, the Filter feature is enabled. If at anytime, you wish to disable the feature temporarily, click on the slider next to the category of elements that are represented on the map. When the slider tab is green, the feature is enabled. When it is gray, it is disabled.
Choose different filters (like Genre, Play, Category and Subcategory of Absent Elements, as well as the Region and Location of the absent elements) to refine your search for absent elements.
Every filter has a dropdown menu that lists all the options within that filter. There is also a search bar to find an option within a specific filter.
Note that more than one filter refines your search, thus satisfying all criteria for the search.