I've been having this problem for a while, keep forgetting to post an issue.

I've got a pretty extensive list of biomes (nearly all the biomes in the modpack, really) for cityBiomeFactors, to have a fine degree of control for where cities can and cannot spawn, as well as affecting density.

I'm having a great deal of trouble with buildings generating in some biomes that are set to 0 in the config file. It's not all biomes, so I'm not really sure what's happening here. I'm relying on the Tellme mod to identify the correct identifiers for the biomes.

A primary example would be the abyssalcraft overworld biomes. Even with these:

    S:cityBiomeFactors <
        darklands=0
        darklands_forest=0
        darklands_plains=0
        darklands_hills=0
        darklands_mountains=0
        coralium_infested_swamp=0

I'm still getting quite a lot of buildings in all of those biomes, and those are as best I can determine the correct identifiers for those biomes.

Currently running lostcities-1.12-1.0.1, on forge 2501.

Hmm only thing I can think is that those are not the right biome names. Other then that I really have no idea

I will check it out but still weird

I am also seeing buildings in ocean chunks, sometimes, despite me also having those set as =0. Not as prevalent as the others, but still happening and kinda awkward.

I'm pretty sure I have the name for that one right.

Hm. Random thought. I need to go over the list to make sure this isn't the case, but hypothetically speaking, if there was a biome specified in that list that no longer existed (due to a mod removal) could it impact lost cities' handling of city biome factors?

Hmm at phone now so can't check but that might indeed be the casr

Well, it's at least an avenue to explore

Well, I just went through all 138 biomes to verify they all are still provided by a mod (or vanilla) in-game, and they are, so that isn't it.

That said, some of them don't actually exist in the overworld. I know for sure I accidentally included things like 'void' (which I can remove), and it's possible some of the other biomes I wasn't sure on might be, say, nether biomes. Would that matter?

I can say with confidence that's not the problem. I'm currently exploring a stripped down environment, where I just have abyssalcraft, biomes o plenty, chisel, ctm, journeymap, and lost cities.
The config I'm using right now only specifies cityBiomeFactors for the overworld abyssalcraft biomes, no others specified, and I'm getting cities in the abyssalcraft biomes.

Going to poke at it some more.

Found the problem, and it's almost entirely a configuration issue, not a code issue (maybe slightly a documentation issue).

Essentially, non-vanilla biome needs to be fully qualified. This is not obvious from config, I would recommend stating that explicitly in the comment for cityBiomeFactors (and possibly allowedBiomeFactors if it's true there as well, for completeness)

    # The default biome factor which is used if your biome is not specified in 'cityBiomeFactors' [range: 0.0 ~ 1.0, default: 1.0]
    S:cityBiomeFactorDefault=1

    # List of biomes with a factor to affect the city factor in that biome. Using the value 0 you can disable city generation in biomes [default: [river=0], [frozen_river=0], [ocean=.7], [frozen_ocean=.7], [deep_ocean=.4]]
    S:cityBiomeFactors <
        abyssalcraft:darklands=0
        abyssalcraft:darklands_forest=0
        abyssalcraft:darklands_plains=0
        abyssalcraft:darklands_hills=0
        abyssalcraft:darklands_mountains=0
        abyssalcraft:coralium_infested_swamp=0
        ocean=0
        biomesoplenty:seasonal_forest=0
     >

This mostly works as expected: city everywhere except non-deep ocean, seasonal forest, and the abyssalcraft biomes.

I'm still having some trouble with cities in 'forbidden' biomes, but this appears to be primarily an issue of buildings/roads spilling into chunks adjacent to allowed biomes. This is the cause of the 'sometimes ocean city' stuff I was seeing before; tiny fractional bit of beach resulting in 3-5 city chunks in the ocean.

I don't know if that is a thing that is addressable.