When I create a world using the custom world presets, the world is empty. When I quit the game and reload it, there is only a flat little area.
The same issue occurs with all presets.
I tried to modify a value manually (and not using presets) and it works well.
I was looking for a way to desactivate advanced openGL, but the option disappeared in this version.

EDIT:
I did several tests today, and it appears that the other presets custom world works (expect caves of chaos and the one with huge moutains).
With floating islands preset, the chunks load very slowly (check the images of 10/03).
So I suppose that the problem with extreme presets custom worlds is also a (even more) slow chunk loading speed.