I've kicked up a similar looking bird 3 times while living in Hainan without being able to get a clear look at it. Each time I immediately thought Cinnamon Bittern but wasn't able to get a picture until the last sighting. Unfortunately this is the best I could do . I was thinking it could also be Yellow Bittern but don't have any experience with this species and am not sure how variable their color is. Any thoughts on this one would be much appreciate. It's been kind of a thorn in my side, honestly.