Selected value in accordion widget is not getting change the parent dashboard filter in Sisense Why?

Instead of the fold-out of another dashboard that is the Accordion, you might consider using a Tabber instead. Tabber shows/hides widgets on the dashboard itself depending on the selected tab from the widget. 

Because the widgets are still on the dashboard itself, you can have the filters from widgets inside the tabber affect the main dashboard even if they get hidden afterward.