Updating a pre-generated world to 1.19+ doesn't generate Deep Dark biomes

I have been running a Minecraft server on Java Edition 1.17.1, and I decided to hold off on updating to 1.18 as 1.19 had been announced with the deep dark biome and ancient cities being an addition to the game.

After extensive testing, I was able to get structures that generate on 1.19 such as the aforementioned ancient cities with the Warden and sculk series of blocks, but the deep dark biome itself would not generate under the old chunks at all.

My map is a custom one made in a third-party world generating program, but the caves below are generated with vanilla properties. Lush cave biomes and the caves themselves generate with no problem, but the deep dark will not generate even when I run /locate.