I would like to suggest that objects in the trellis container react/respond to selections made in a filter pane outside the trellis container, so that when I select a value in the filter pane (for instance an education), I get to see only vizualisations of the possible values of the dimension used in the Trellis container (for instance the three geographical location of the education selected in the filter pane). As the Trellis container works right now (Qlik Sense September 2020 release), I get to see all values of the dimension used in the Trellis container (ten geographical locations), regardless of my selection in the filter pane. The filter pane is outside of the Trellis container, thus a seaparate object on the sheet.
I do not know if this current behaviour is actually a bug in Qlik Sense.