Ominous vaults occasionally still don't generate in chamber_1, even though the changelog of 1.21.30.21 states that this problem was fixed. 

From the changelog of 1.21.30.21:

• Fixed Ominous Vault may fail to generate in Pedestal and chamber_1/2

Steps to reproduce:

1. Create a world with this seed: -2275744594652264290
2. Go to coordinates -2450 -15 5660
3. Look for an ominous vault within the room

Observed result:
The room does not have an ominous vault.

Expected result:
The room should have an ominous vault.