Angular 10 lazy loading routing not working

I can not figure out why this scenario works and not the following one.

Scenario 1: This loads the CasesModule component correctly for the module.

NavigationEnd(id: 2, url: '/cases', urlAfterRedirects: '/cases/current')

app-routing.modules.ts:

import { NgModule } from "@angular/core";
import { Routes, RouterModule } from "@angular/router";

const routes: Routes = [
   {
    path: "cases",
     loadChildren: () => import("./cases/cases.module").then(m => m.CasesModule)
   },
  { path: "**", redirectTo: "", pathMatch: "full" }
];

@NgModule({
  imports: [RouterModule.forRoot(routes, { enableTracing: true })],
  exports: [RouterModule]
})
export class AppRoutingModule {}

cases.routing.modules:

import { NgModule } from '@angular/core';
import { CommonModule } from '@angular/common';
import { Routes, RouterModule } from '@angular/router';
import { CurrentCasesComponent } from './current-cases/current-cases.component';

const routes: Routes = [
    { path: '', redirectTo: 'current', pathMatch: 'full' },
    {
      path: 'current',
      component: CurrentCasesComponent,
    },
];

@NgModule({
  declarations: [],
  imports: [RouterModule.forChild(routes)],
  exports: [RouterModule],
})
export class CasesRoutingModule {}

Scenario 2:

I want to load the module routes dynamically since I am importing the modules dynamically using SystemJs import.

The main difference are: app-routing.modules.ts:

import { NgModule } from "@angular/core";
import { Routes, RouterModule } from "@angular/router";

const routes: Routes = [
  // {
  //   path: "cases",
  //   loadChildren: () => import("./cases/cases.module").then(m => m.CasesModule)
  // },
  { path: "**", redirectTo: "", pathMatch: "full" }
];

@NgModule({
  imports: [RouterModule.forRoot(routes, { enableTracing: true })],
  exports: [RouterModule]
})
export class AppRoutingModule {}

I would like to load the route with a component or service.

app.component.ts

import { Component, VERSION } from "@angular/core";
import { Route, Router } from "@angular/router";

@Component({
  selector: "app-root",
  templateUrl: "./app.component.html",
  styleUrls: ["./app.component.scss"]
})
export class AppComponent {
  constructor(private router: Router) {}

  route() {
    this.createRoute();
    // test navigation
    this.router.navigate(["cases"]);
  }

  createRoute() {
    const appRoutes = [...this.router.config];
    const route: Route = {
      path: "cases",
      loadChildren: () =>
        import("./cases/cases.module").then(m => m.CasesModule)
    };
    appRoutes.push(route);
    this.router.resetConfig(appRoutes);
  }
}

app.component.html

<button  (click)="route()">cases</button>
<app-shell></app-shell>

I can see the route is loaded correctly in the router config, but it doesn't create the _LoadedConfig when I invoke the route and redirect to the default page instead.

NavigationEnd {id: 2, url: "/cases", urlAfterRedirects: "/"}

Here is the link to an example reproducing the issue: StackBlitz

What am I missing?