Tabs don't load when upgrading from Angular 6 to 6.1

Bug Report

Ionic Info Run ionic info from a terminal/cmd prompt and paste the output below.

Ionic:

   ionic (Ionic CLI)          : 4.0.6 (/usr/local/lib/node_modules/ionic)
   Ionic Framework            : @ionic/angular 4.0.0-beta.2
   @angular-devkit/core       : 0.7.3
   @angular-devkit/schematics : 0.7.3
   @angular/cli               : 6.1.3
   @ionic/ng-toolkit          : 1.0.6
   @ionic/schematics-angular  : 1.0.2

Cordova:

   cordova (Cordova CLI) : 8.0.0
   Cordova Platforms     : android 7.0.0, ios 4.5.4

System:

   NodeJS : v10.8.0 (/usr/local/bin/node)
   npm    : 6.3.0
   OS     : macOS High Sierra
   Xcode  : Xcode 9.4.1 Build version 9F2000

Environment:

   ANDROID_HOME : not set

Describe the Bug I’ve updated my app from Angular 6 to Angular 6.1, because the ionic-conference-app got this update too. Before the update, the lazy loaded tabs were displayed and everything was working fine. Now, only the TabsPage is loaded, all lazy loaded tabs are not.

Steps to Reproduce Steps to reproduce the behavior:

1. Checkout ionic-conference-app on branch core-update
2. Modify the routes described in tabs-page-routing.module.ts to use lazy loading:

This is the route configuration, that does work with Angular 6.0.2 and 6.1.2

{
    path: 'schedule',
    component: SchedulePage,
    outlet: 'schedule'
},

This one only works with Angular 6.0.2:

{
    path: 'schedule',
    outlet: 'schedule',
    loadChildren: '../schedule/schedule.module#ScheduleModule'
}

1. See, that the Schedule page is not being loaded anymore

I’ve used this article to create tabs that are lazy loaded

Expected Behavior The tabs get loaded with Angular 6 and 6.1

[MrSparklle]

@carstenbaumhoegger @kensodemann Sorry guys. I tought the lazy loading was implemented by default in tabs started but seems it’s not. I made a research this morning and this issue is being treated in this issue https://github.com/ionic-team/ionic/issues/14566

[kensodemann]

Duplicated here: https://github.com/kensodemann/car-show-ballot-box/tree/test/lazyLoading

If I take this project anywhere above 6.0.4 (IOW, 6.0.5 or higher, including 6.1.2) it exhibits the issue reported here. However, this appears to be an issue with the Angular router and not an issue with Ionic itself.

EDIT: upon reviewing with the team, there could be an issue on the Ionic end as well. More work is being done to look into that.