When trying to create a new world using the Customized world type, the Lava Oceans setting does not stay set and you cannot generate a world with lava oceans as a result. After toggling the setting to Yes, if you leave that page of options by any means and then return, it will be set to No. Going to the Presets screen and manually changing the setting from False to True does not work either, and the preset world type "Good Luck" which should have lava oceans does not set the value either.