title: How to resolve 'ion-item' is not a known element in ionic
body: <p>i am building an app with ionic, i noticed that when i want to convert my app to apk, the ionic elements like <code>ion-header, ion-title, ion-list etc</code> stops working in the modal. it works on other pages except in the modal</p>
  <p>here is the code for comment.module.ts</p>
  <pre><code>import { NgModule, CUSTOM_ELEMENTS_SCHEMA } from '@angular/core';
  import { IonicModule } from '@ionic/angular';
  import { CommonModule } from '@angular/common';
  import { FormsModule } from '@angular/forms';
  import  { NgxEmojModule } from 'ngx-emoj';
  import { TimeAgoPipe } from 'time-ago-pipe';
  
  import { CommentPageRoutingModule } from './comment-routing.module';
  import { CommentPage } from './comment.page';
  import { PipesModule } from '../../pipes/pipes.module';
  
  @NgModule({
    imports: [
      CommonModule,
      NgxEmojModule,
      PipesModule,
      FormsModule,
      IonicModule,
      CommentPageRoutingModule
    ],
      schemas: [CUSTOM_ELEMENTS_SCHEMA],
    declarations: [
      CommentPage,
          TimeAgoPipe]
  })
  export class CommentPageModule {}
  </code></pre>
  <p>I added <code>CUSTOM_ELEMENTS_SCHEMA</code> in both the app module and the page module, but its not just working.</p>
  <p>here is the comment.page.html</p>
  <pre><code>&lt;ion-header class=&quot;ion-no-border&quot; *ngIf=&quot;!isLoading&quot;&gt;
      &lt;ion-toolbar&gt;
          &lt;ion-title class=&quot;centerAM&quot;&gt;{{no_comm | shortNumber}} comment{{no_comm&gt;1?'s':''}}&lt;/ion-title&gt;
      &lt;/ion-toolbar&gt;
  &lt;/ion-header&gt;
  &lt;ion-content&gt;
  ....
  </code></pre>
  <p>I am getting this when i try to convert it to apk</p>
  <pre><code>src/app/modal/comment/comment.page.html:1:1 - error NG8001: 'ion-header' is not a known element:
  1. If 'ion-header' is an Angular component, then verify that it is part of this module.
  2. If 'ion-header' is a Web Component then add 'CUSTOM_ELEMENTS_SCHEMA' to the '@NgModule.schemas' of this component to suppress this message.
  
  1 &lt;ion-header class=&quot;ion-no-border&quot; *ngIf=&quot;!isLoading&quot;&gt;
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  
    src/app/modal/comment/comment.page.ts:7:16
      7   templateUrl: './comment.page.html',
                       ~~~~~~~~~~~~~~~~~~~~~
      Error occurs in the template of component CommentPage.
  src/app/modal/comment/comment.page.html:2:2 - error NG8001: 'ion-toolbar' is not a known element:
  1. If 'ion-toolbar' is an Angular component, then verify that it is part of this module.
  2. If 'ion-toolbar' is a Web Component then add 'CUSTOM_ELEMENTS_SCHEMA' to the '@NgModule.schemas' of this component to suppress this message.
  
  2  &lt;ion-toolbar&gt;
  </code></pre>
  <p>here is the code where i called up the modal</p>
  <pre><code>async CommentModal(id) {
      const modal = await this.modalController.create({
          component: CommentPage,
          componentProps:{id},
          swipeToClose: true,
          cssClass: 'comment-modal'
      });
      await modal.present();
      return 
  }
  </code></pre>
  <p>here is the comment.page.html page</p>
  <pre><code>&lt;ion-header class=&quot;ion-no-border&quot; *ngIf=&quot;!isLoading&quot;&gt;
      &lt;ion-toolbar&gt;
          &lt;ion-title class=&quot;centerAM&quot;&gt;{{no_comm | shortNumber}} comment{{no_comm&gt;1?'s':''}}&lt;/ion-title&gt;
      &lt;/ion-toolbar&gt;
  &lt;/ion-header&gt;
  &lt;ion-content&gt;
      &lt;ng-container *ngIf=&quot;isLoading; else loadTemp;&quot;&gt;
          .....
      &lt;/ng-container&gt;
      &lt;ng-template #loadTemp&gt;     
          &lt;ion-item *ngFor=&quot;let comm of comms&quot; lines=&quot;none&quot;&gt;
              ....
          &lt;/ion-item&gt;
      &lt;/ng-template&gt;
  &lt;/ion-content&gt;
  &lt;ion-footer *ngIf=&quot;isLoggedIn&quot;&gt;
      &lt;ion-toolbar&gt;
          &lt;ng-container *ngIf=&quot;showEm&quot;&gt;
              ....
          &lt;/ng-container&gt;
          &lt;ion-grid&gt;
              &lt;ion-row&gt;
                  .....
              &lt;/ion-row&gt;
          &lt;/ion-grid&gt; 
      &lt;/ion-toolbar&gt;
  &lt;/ion-footer&gt;
  </code></pre>
  <p>Pls what am i doing that is wrong</p>