Holes in the distance. Some chunks not showing up.
I've pre generated this singleplayer JJthunder to the max world using chunky. The world looks like in the picture. Even if i move to the affected area and then back it still looks like this.

Solution
Single Player:
- Overworld:
.minecraft/saves/WORLD_NAME/data/DistantHorizons.sqlite - Nether:
.minecraft/saves/WORLD_NAME/DIM-1/data/DistantHorizons.sqlite - End:
.minecraft/saves/WORLD_NAME/DIM1/data/DistantHorizons.sqlite - Custom Dimensions:
.minecraft/saves/WORLD_NAME/DIMENSION_FOLDER/data/DistantHorizons.sqlite
.minecraft/Distant_Horizons_server_data/SERVER_NAME/