In the World Customization when selecting a biome for the World Type: Single Biome, the Pale Garden is missing as an option for world generation.

To reproduce:

• Launch Minecraft snapshot 24w40a
• Create New World
• Go to Experiments and turn on Winter Drop, click Done
• Go to World -> World Type: Single Biome
• Go to Customize and scroll to where the Pale Garden should be located above Plains
• 
• 
•