Try this

Author: NullVoxPopuli

addon/src/settled.ts

@@ -190,19 +190,24 @@ if (loader.registry['ember-testing/test/waiters']) {
 function checkWaiters() {
   // eslint-disable-next-line @typescript-eslint/no-unsafe-function-type
   type Waiter = [any, Function];
-  const EmberTest = Ember.Test as any as { waiters: Array<Waiter> };
+  const EmberTest = Ember.Test as any as {
+    waiters: Array<Waiter>;
+    checkWaiters: () => boolean;
+  };
 
   if (_internalCheckWaiters) {
     return _internalCheckWaiters();
-  } else if (EmberTest.waiters) {
+  }
+
+  if (EmberTest.waiters) {
     if (
       EmberTest.waiters.some(([context, callback]) => !callback.call(context))
     ) {
       return true;
     }
   }
 
-  return false;
+  return EmberTest.checkWaiters();
 }
 
 export interface SettledState {

test-app/ember-cli-build.js

@@ -39,9 +39,6 @@ module.exports = function (defaults) {
           '{{inner-comp}}': { safeToIgnore: true },
           '{{template-only}}': { safeToIgnore: true },
         },
-        helpers: {
-          '{{jax}}': { safeToIgnore: true },
-        },
       },
     ],
   });

test-app/tests/unit/setup-rendering-context-test.js

@@ -87,7 +87,6 @@ module('setupRenderingContext', function (hooks) {
         'component:js-only': Component.extend({
           classNames: ['js-only'],
         }),
-        'helper:jax': helper(([name]) => `${name}-jax`),
         'component:outer-comp': setComponentTemplate(
           hbs`outer{{inner-comp}}outer`,
           class extends Component {}
@@ -287,15 +286,21 @@ module('setupRenderingContext', function (hooks) {
     });
 
     test('can invoke helper', async function (assert) {
-      await render(hbs`{{jax "max"}}`);
+      this.setProperties({
+        jax: helper(([name]) => `${name}-jax`),
+      });
+      await render(hbs`{{this.jax "max"}}`);
 
       assert.equal(this.element.textContent, 'max-jax');
     });
 
     test('can pass arguments to helper from context', async function (assert) {
+      this.setProperties({
+        jax: helper(([name]) => `${name}-jax`),
+      });
       this.set('name', 'james');
 
-      await render(hbs`{{jax this.name}}`);
+      await render(hbs`{{this.jax this.name}}`);
 
       assert.equal(this.element.textContent, 'james-jax');
     });