I'm creating FeatureLayer objects from SubLayer objects in order to use them as sources in a Search widget. One of the FeatureLayer objects seems to work properly as a source while the other two don't. I originally added them as sources without using the then method callback on the FeatureLayer objects. I then tried adding them within the then method callback and none of them got added because the Promises never resolved. I then wrote some test code with a completely different MapServer and the same thing happens.
Does anyone know why the FeatureLayer Promise isn't resolving?