When working with Dashboards in 11.1.5, you can drag over a data item onto your dashboard and it creates what looks like a prompt control.
One issue when using this as a prompt is that if you have the data item in a visualization on the dashboard, it does not filter the widget, it selects or highlights.
If you want to filter the widget, you can add the data item to the filter area instead:
That works and is helpful but we originally wanted the control on the dashboard page.
If we click on the filter, we can add it to the canvas.
Now if you make your selection, you will see the filtered visualization based on a prompt control on the dashboard canvas.
I hope that helps!