1. Customize the Incident popup view layout by going to the URL <your instance name>.service-now.com/incident.do?sysparm_view=sys_popup.

2. Add the Activities (filtered) formatter to the Sys_popup view.

   1. Navigate to Configure > Form Layout.
   2. Scroll down in the slushbucket and add the Activities (filtered) formatter to the form.
   3. Click Save.

3. Add a name in the required Caller field and click Save in the Incident popup view window.

4. Go to an Incident list.

5. Hover over the reference icon () of any incident record in the list.

   Note that the Activity feed is omitted from the popup view.

This is expected behavior: the UI16 design features a new activity stream.