Problem with permissions in REST API

I created dev cloud with project and some tasks for test.
After successful authorization I tried to search for issues with access token (POST):

With body

  "jql": "assignee = currentUser()",
  "startAt": 0,
  "fields": [
  "fieldsByKeys": false

As result I got

    "message": "Client must be authenticated to access this resource.",
    "status-code": 401

How is it possible?
Exactly, I authorized with suitable scope for my dev cloud as described in article.

For test I tried to do it via Postman after getting token via my app.
Please help.