strange flatmap behaviour

flatmap.js

const request = require('superagent');
const _ = require('lodash');
const H = require('highland');
const Promise = require('bluebird');
function getLocations() {
    const call = request
        .get('http://viatorapi.viator.com/service/taxonomy/locations')
        .query({apiKey: API_KEY})
    return Promise.resolve(call)
        .then((res) => res.body.data)
}

const callDetail = (id) =>
  Promise.resolve(
    request
      .get('http://viatorapi.viator.com/service/attraction')
      .query({apiKey: '2697384146408674701', seoId: id, currencyCode: 'EUR'})
  )
  .then(x => x.body.data)
  .then(function(x) {
    if(_.isNull(x)) {
      throw null
    }
    return x
  })
  .catch(function(e) {
    return Promise.delay(500).then(()=> callDetail(id))
  })


function getAttractionsByLocation(id) {
    return Promise.resolve(
        request
          .post('http://viatorapi.viator.com/service/search/attractions')
          .query({apiKey: API_KEY})
          .send({destId: id})
    )
    .then(res => res.body.data)
    .catch(e => console.log(e))
}


function populate(create) {
    return H(
        getLocations()
    )
    .flatten()
    .map(x => x.destinationId)
    .map(x => H(getAttractionsByLocation(x)))
    .flatten()
    .each(x => console.log(x.length))
}

if (require.main === module) {
    populate(console.log)
}