Pressing 'Defaults' in customized world settings makes options unresponsive

The bug

After clicking the 'Defaults' button in the customized world settings UI, the options become unresponsive to all mouse and keyboard input.

How to reproduce

1. Open the create world page
2. Select world type Customized
3. Open the 'Customize World Settings' UI
4. Change some settings or click 'Randomize'
5. Click 'Defaults'
6. Try to change the settings manually

Backing out of the customize settings page and reopening it will make the options responsive again.