Sinkhole leads to to identical world

I had the same problem. It's a bug, but as a workaround, when creating your World, for the Caves Settings, when you change things, don't click Save as a Preset. Or, you can just not make any changes to the caves, that would work too.

For the devs,

I looked into it a bit, and I'm writting it here to save you time looking yourselves:

wolrdgenoverride.lua when creating caves, changes a setting but not saving as preset:

return { misc={ world_size="huge" }, override_enabled=true, preset="DST_CAVE" }

worldgenoverride.lua when saving settings as preset:

return { override_enabled=true, preset="CUSTOM_PRESET_3" }

and from saveindex:

actualpreset="CUSTOM_PRESET_3",
            preset="DST_CAVE",
            presetdata={
              basepreset="DST_CAVE",
              data="CUSTOM_PRESET_3",
              desc="Custom preset 3. Your world, your rules!",
              location="cave",
              overrides={
                { "task_set", "cave_default" },
                { "start_location", "caves" },
                { "waves", "off" },
                { "layout_mode", "RestrictNodesByKey" },
                { "wormhole_prefab", "tentacle_pillar" },
                { "world_size", "huge" } 
              },
              text="Custom Preset 3" 
            },
            tweak={  } 

So, even though location is stored correctly as "cave", I guess for custom presets it ignores that and creates a forest anyway.

Hope this help a bit,

Keep up the amazing work;)

Aris