When I generate a new world in the latest snapshot, only normal Oceans and Deep Oceans generate, but not the new warm, cold and frozen oceans (including Deep variants). I do not know if this is truly a bug, because I've seen a lot of video's about the new snapshot that do have these oceans, but I don't know if these are newly generated worlds.
I haven't attached any screenshots, because I think the description explains it.
Environment
Windows 10
Java 8
Snapshot 18w15a, Vanilla
Duplicate of MC-128260