[MC-252863] ancient_city Structure ID incompatible with explorer map loot table functions

If you attempt to create a custom explorer map leading to an ancient city using the loot table functions, it doesn't recognize "ancient_city" as an id. Here's the code I was using:

          "type": "minecraft:item",
          "weight": 3,
          "functions": [
            {
              "function": "minecraft:exploration_map",
              "destination": "ancient_city",
              "decoration": "red_x",
              "zoom": 1,
              "skip_existing_chunks": false
            },
            {
              "function": "minecraft:set_name",
              "name": {
                "translate": "filled_map.buried_treasure"
              }
            }
          ],
          "name": "minecraft:map"
        },

Perhaps this is just an issue on my part? I'm not exactly a great coder.