The World Seed, Seed Templates, Flat World, Starting Map, and Bonus Chest options becomes available after unlocking the Marketplace Templates settings in the new Create New World Screen.

How to reproduce:

1. Create a new world with a Marketplace Template with the Old Create New World Screen
2. Unlock the creators settings
3. Observe the World Seed, Seed Picker, Flat World, Starting Map, and Bonus Chest options still grayed out
4. Go to the New Create New World Screen with a Marketplace Template
5. Go to the Advanced Tab
6. Unlock the Creators Settings
7. Observe the World Seed, Seed Templates, Flat World, Starting Map, and Bonus Chest options becoming available

Observed results:

The World Seed, Seed Templates, Flat World, Starting Map, and Bonus Chest options becomes available, causing glitchy behavior

Expected results:

The World Seed, Seed Templates, Flat World, Starting Map, and Bonus Chest should still be grayed out after unlocking the creators settings, matching the Old UI