In the Customized world settings, the biome selection doesn't work properly.

When I'm in the Customized world settings, I would set the biome to a certain biome, let's say, Jungle. Then, I would click "Done", and then I would go back to the Customized settings, and noticed that the biome selection changed.

How to reproduce; I've actually made a video walkthrough of it:
http://youtu.be/Vms_3ixcfIQ