Can't use 1.18 preview datapack on realms

Can't use 1.18 preview datapack on realms.

 

Title says it all, me and my friends where trying to play the new 1.17 update on our realm, and really wanted to use the datapack to get the world generation. But everytime we tried uploading a world with said datapack on it, the world would just reload without the new cave generation.