isFetching JS query property not working (value is "false" when running the query all the time)

Goal: Using the isFetching property from a JS query to condtionally display UI elements

Steps: Implemented the sample from the web app tutorial (Web app tutorial | Retool Docs) and trying to react on the isFetching property from the blockAll query (conditionally displaying a UI element)
When running the query isFetching is not getting the value "true", it remains "false".

Details:
Here is the code for the blockUsers JS query which I implemented:

return (async () => {
var rows = table1.data;

const unblockedUsers = rows
  .map((row, index) => [row, index])
  .filter(([row]) => !row.blocked);

let blockIndex = 0;

const blockNext = () => {
  // Notify and quit when finished
  if (blockIndex >= unblockedUsers.length) {
    utils.showNotification({
      title: "Success",
      description: "Successfully blocked " + unblockedUsers.length + " users.",
      notificationType: "success",
      duration: 3,
    });

    // Update table after queries finish

    getUsers.trigger();
    
    return;
  }

  // Get next unblocked user and unblock them
  const [unblockedUser, index] = unblockedUsers[blockIndex];
  statusText.setValue("Blocking user " + unblockedUser.name);
  blockAllUsers.trigger({
    additionalScope: { i: index },
    onSuccess: function () {
      blockIndex++;
      blockNext();
    },
  });
};

blockNext();
})();

I've tries both, embedding it in "return (async () => {...}) " and without. When trying to use the isFetching property from the JS query I ran into the problem that isFetching is not set to true when running the query. The value remains "false" all the time. Conditionally displaying a UI element based on that isFetching property is therefore not working as it never updates to "true".

Why is isFetching not working?