Why doesn't my jigsaw connection work, when it worked in the past?

I have done other jigsaw based structures before. Even managed to do a quite complex one, but now, it doesn't want to work. What could be the problem? The jigsaws point to each other, I double checked everything, I'm out of ideas.
I try to make hexagons generate next to each other 
Structure set: {     "placement": {       "type": "minecraft:random_spread",       "salt": 14357618,       "separation": 5,       "spacing": 9     },     "structures": [       {         "structure": "b723:hex_pillars",         "weight": 1       }     ]   }
structure:
    "type": "minecraft:jigsaw",
    "biomes": [
      "b723:wastes-1"
    ],
    "step": "surface_structures",
    "spawn_overrides": {},
    "terrain_adaptation": "beard_thin",
    "start_pool": "b723:hex_origin",
    "size": 7,
    "start_height": {
      "absolute": 0
    },
    "project_start_to_heightmap": "WORLD_SURFACE_WG",
    "max_distance_from_center": 80,
    "use_expansion_hack": true
  }```