title: reportProgress is not working in production
body: <p>When I'm uploading video file, it works normally on local (develop mode). But when i'm uploading it to the server (prod), it doesn't work.<br>
  Here is the service:</p>
  
  <pre><code>uploadVideo(id: String, file, imageId) {
          let formData = new FormData();
          formData.append('video', file);
          formData.append('imageId', imageId);
          return this.http.post&lt;any&gt;(`.../${id}/video`, formData, {reportProgress: true, observe: 'events'})
                  .pipe(map(response =&gt; {
                          return response;
                  }));
      }
  </code></pre>
  
  <p>Here is the component -></p>
  
  <pre><code>this.arrivalProductService.uploadVideo(this.data.id, this.selectedFile, imageId)
        .pipe(
          map((event) =&gt; {
            console.log('event', event);
            if(event.type === HttpEventType.UploadProgress){
              const percentDone = Math.round(100 * event.loaded / event.total);
              return { status: 'progress', message: percentDone };
            }
            if (event.type === HttpEventType.Response) {
              return event.body;
            }
          }),
          catchError(error =&gt; {
            return throwError(error);
          }),
          finalize(() =&gt; {
            console.log('completed');
          })
        )
        .subscribe(
          data =&gt; {
            ....
         })
  </code></pre>
  
  <p>If I'm logging event on map(), on local dev it return all progress: like ({status: 'progress', message: 0}, ... etc), on production it returns nothing.. <br>
  I can't understand what's wrong with the code.. please help me</p>