ElasticSearch Rails resource_already_exists_exception when running tests

I'm trying to run one of my tests, which makes a search, trying to assert the inclusion of records in the search result, but in the meantime, I'm receiving a Elasticsearch::Transport::Transport::Errors::BadRequest error:

SearchTest#test_simple_test_returns_product:
Elasticsearch::Transport::Transport::Errors::BadRequest: [400] 

{
  "error":{
    "root_cause":[
      {
        "type":"resource_already_exists_exception",
        "reason":"index [app_application_test_products/FTt1YC6eQrCw2XwJuqjmDw] already exists",
        "index_uuid":"FTt1YC6eQrCw2XwJuqjmDw",
        "index":"app_application_test_products"
      }
    ],
    "type":"resource_already_exists_exception",
    "reason":"index [app_application_test_products/FTt1YC6eQrCw2XwJuqjmDw] already exists",
    "index_uuid":"FTt1YC6eQrCw2XwJuqjmDw",
    "index":"app_application_test_products"
  },
  "status":400
}

When I perform a search in development, it works as expected, but in tests is throwing such error, within the test I've added an import and an index refresh, nothing else:

class SearchTest < ActiveSupport::TestCase
  setup do
    Product.import force: true
    Product.__elasticsearch__.refresh_index!
  end

  test "simple test returns product" do
    product = products(:one)
    I18n.locale = product.market.lang
    search = Search.new(
      category: product.category.custom_slug,
      page: 1,
      market_id: product.market_id,
      status: "active",
      seed: Date.today.to_time.to_i
    )
    assert_includes search.results.records, products(:one)
    assert_includes search.results.records, products(:two)
    assert_not_includes search.results.records, products(:three)
  end
end

Any help is appreciated, as any hint to improve the code.

I'm using:

# Gemfile
gem 'minitest', '5.10.1'

# Gemfile.lock
elasticsearch (6.1.0)
elasticsearch-model (6.0.0)
elasticsearch-rails (6.0.0)
minitest (= 5.10.1)

I had the wrong mappings in my model. Instead using the type option, I was using index, what made ElasticSearch to create a multiple mapping. Which isn't available since the version 6.4 (I guess).