If you wish to have the same map counting rooms that spread across multiple scenes you will need to create a SpriteDictionary. This stores references to sprite overrides used by one scenes so that they can be loaded in to the map shown on another scene.
To create a Sprite Dictionary
1. Create a new GameObject and name it SpriteDictionary.
2. Add the SpriteDictionary component to this GameObject
3. Make a prefab from your SpriteDictionary by dragging to the project hierarchy.
4. Add this prefab to all scenes using the map.
Maintaining the SpriteDictionary
The SpriteDictionary will be automatically updated when you assign a sprite to a MapRoom or PointOfInterest however its important that you click the Apply button on the SpriteDictionary GameObject to ensure that the prefab is updated and thus making updates available to all scenes.
Alternatively you can manually drag the sprites you want to use on your map in to the list on the SpriteDictionary component and then hit Apply to apply the changes to the prefab.
TIP: If the sprite dictionary is not correctly updated you will see that the rooms in the UI appear but have the incorrect sprite.
REMEMBER: To support multiple scenes and the SpriteDictionary all of your map and point of interest sprites must have unique names.