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The map reads the standard story Location field.
If you are using custom Location field rather than the standard Location field, your stories will only be shown on the map if you are using the standard Location field for the story’s project.
You can edit a survey and add the standard Location field to it
Select My Apps in the top menu
Select Maps
Tick the Individual Stories checkbox
The map updates to show
Purple pins with the location of each story
The total number of stories that are displayed on the map
You can filter the stories shown by clicking Timeline Filters
The Filters Overlay appears on the right side
Use the toggles to open the available filters and set criteria for the stories you want displayed on the map.
Click Apply to apply the filters
This causes the map to update and the number of stories displayed to adjust
Click Reset to reset the filters