How can I make entityQuery('commerce_order') return completed orders?

Question

Under Drupal Commerce 8.x-2.13 I find that the query

Drupal::entityQuery('commerce_order') 

with no conditions attached returns ONLY incomplete orders (when called in the context of an API endpoint) - and if I apply any parameters exclusive of incomplete orders such as

$query->condition('state', 'completed');

it returns nothing. How can entityQuery be made to retrieve data on completed orders?

Answer 1

The solution is apparently to add $query->accessCheck(FALSE);.