Have an interesting one here:
1) following the example of the map style tutorial
2) Two layers each created from the same "data"
3) one was used as a basemap
4) the second had a filter dynamically applied to show selection
The feature collection was created by hand:
SimpleFeatureCollection collection = FeatureCollections.newCollection();
And populated from a CSV file.
And then two layers were created:
baseLayer = FeatureLayer(collection, style);
And the selectLayer was never rendered; not sure why.
The solution was to read in a second FeatureCollection and allow each layer to operate independently.