The Classes filter group in the Filter Pane of the Impact Analysis - Universe tab consists of a checkbox list with search filter:

With this filter, you can limit the displayed BI data to the objects which belong to the selected universe class(es).

There can be several classes of the same name in different environments or universes.

Start typing a class name you are looking for in the Quick Search control, and the list will be limited to classes that contain your input.

There is an additional item (All) in the list of classes. Use it to toggle between all classes being selected and all classes being unselected.

If all classes are selected, or none of them, then the Classes filter is not applied, and it does not limit the data displayed.

 

 
See also

Universes