I set a two field UniqueValueRenderer for featurelayer, the first field has a vaule, the Second field may has a vaule equals null. the problem is when the second field value is null, the featurelayer render the default value.
Can you share what your desired result would be when a null value is encountered in either of the fields utilized by your UVR?
Handling null values is the primary use case for a default value/symbol. This allows those features to still be rendered with a symbol and appear on the map but otherwise imply they don't fall within the UniqueValues range that has been set.
