Vue js, Vue js method returning undefined

I have a vue class

export default {
  data() {
    return {
      tasks: [],
      currentSort:'name',
      currentSortDir:'asc',
      companies: []
    };
  },
  async created() {
    this.storage.tasks++;
    try {
      this.tasks = await Monitor.Task.getTasks();
      this.companies = await Monitor.getCompanies();
    } catch (code) {
      this.notify("danger", "Не удалось загрузить задачи", code);
    } finally {
      this.storage.tasks--;
    }
  },
  computed: {
    mappedTasks() {
      return _.chain(this.tasks)
          .sort((a,b) => {
            let modifier = 1;
            if(this.currentSortDir === 'desc') modifier = -1;
            if(a[this.currentSort] < b[this.currentSort]) return -1 * modifier;
            if(a[this.currentSort] > b[this.currentSort]) return 1 * modifier;
            return 0;
          })
          .map(it => {
            let statusText;
            switch (it.status) {
              case "NOT_COMPLETED":
                statusText = "Ожидает выполнения";
                break;
              case "COMPLETED":
                statusText = "Завершено";
                break;
              case "CANCELED":
                statusText = "Отменено";
                break;
              default:
                statusText = "Неизвестно";
            }
            const companyName = this.getCompanyById(it.companyId).name;

            let updated
            if(it.updatedAt !== null) {
              updated = Moment(it.updatedAt).utcOffset(TIME_ZONE).format("YYYY-MM-DD HH:mm:ss")
            }

            const values = {
              statusText,
              createdAt: Moment(it.createdAt).utcOffset(TIME_ZONE).format("YYYY-MM-DD HH:mm:ss"),
              updatedAt: updated,
              companyId: companyName
            };


            return _.assign({}, it, values);
          })
          .value();
    },
  },
  methods: {
    sort:function(s) {
      if(s === this.currentSort) {
        this.currentSortDir = this.currentSortDir==='asc'?'desc':'asc';
      }
      this.currentSort = s;
    },
    getCompanyById(id) {
      return this.companies.find(company => company.id === id);
    }
  }
}

The proplem that in method getCompanyById this.companies is undefined therefore method doens’t return company. I tried to make to make method async and like this:

async getCompanyById() {
  let  companies = await Monitor.getCompanies()
  return companies
}

In this case, I have that status of companies is pending. I don’t undenstand why in computed.mappedTask I can’t get companies from async created unlike tasks