Difícil de explicar isso. Eu tinha um exemplo modal de trabalho simples ng2-bootstrap funcionando. Eu o expandi para incluir o modelo de exemplo do Boostrap 4 Jumbotron para minha página inicial, agora o modal ng2-bootstrap não faz nada. Eu posso ver othis.childModal.show() noO componente modal filho está sendo chamado ao clicar no botão, mas nada acontece. Nenhum erro no console do Chrome e nenhum programa modal. Eu não tenho idéia do que fazer em seguida :-/

// ============================================================================
// /src/app/app.module.ts

import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
import { FormsModule } from '@angular/forms';
import { HttpModule } from '@angular/http';
import { ModalModule } from 'ng2-bootstrap/modal';
import { NgbModule } from '@ng-bootstrap/ng-bootstrap';

import { AppComponent } from './app.component';
import { DemoModalChildComponent } from './demo-modal-child.component';

@NgModule({
    declarations: [
        AppComponent, DemoModalChildComponent
    ],
    imports: [
        BrowserModule,
        FormsModule,
        HttpModule,
        NgbModule.forRoot(),
        ModalModule.forRoot()
    ],
    bootstrap: [AppComponent]
})
export class AppModule { }


// ============================================================================
// /src/app/app.component.ts

import { Component } from '@angular/core';

@Component({
    selector: 'app-root',
    templateUrl: './app.component.html',
    styleUrls: ['./app.component.css']
})
export class AppComponent {
    title = 'app works!';
}



<!-- ========================================================================== -->
<!-- /src/app/app.component.html -->

<nav class="navbar navbar-toggleable-md navbar-inverse fixed-top bg-inverse">
    <button class="navbar-toggler navbar-toggler-right" type="button" data-toggle="collapse" data-target="#navbarsExampleDefault"
        aria-controls="navbarsExampleDefault" aria-expanded="false" aria-label="Toggle navigation">
        <span class="navbar-toggler-icon"></span>
        </button>
        <a class="navbar-brand" href="#">Navbar</a>

        <div class="collapse navbar-collapse" id="navbarsExampleDefault">
            <ul class="navbar-nav mr-auto">
                <li class="nav-item active">
                    <a class="nav-link" href="/home">Home <span class="sr-only">(current)</span></a>
                </li>
                <li class="nav-item">
                    <a class="nav-link" (click)="showLoginModal()">Login</a>
                </li>
                <li class="nav-item">
                    <a class="nav-link" href="/members">Players</a>
                </li>
                <li class="nav-item">
                    <a class="nav-link" href="/game">Game</a>
                </li>
                <li class="nav-item">
                    <a class="nav-link disabled" href="#">Disabled</a>
                </li>
                <li class="nav-item dropdown">
                    <a class="nav-link dropdown-toggle" href="http://example.com" id="dropdown01" data-toggle="dropdown" aria-haspopup="true"
                        aria-expanded="false">Dropdown
                        </a>
                        <div class="dropdown-menu" aria-labelledby="dropdown01">
                            <a class="dropdown-item" href="#">Action</a>
                            <a class="dropdown-item" href="#">Another action</a>
                            <a class="dropdown-item" href="#">Something else here</a>
                        </div>
                </li>
            </ul>
            <form class="form-inline my-2 my-lg-0">
                <input class="form-control mr-sm-2" type="text" placeholder="Search">
                <button class="btn btn-outline-success my-2 my-sm-0" type="submit">Search</button>
            </form>
        </div>
</nav>

<!-- Main jumbotron for a primary marketing message or call to action -->
<div class="jumbotron">
    <div class="container">
        <demo-modal-child #c="child"></demo-modal-child>
        <button type="button" class="btn btn-primary" (click)="c.showChildModal()">Open child modal</button>
        <h1 class="display-3">Hello, world!</h1>
        <p>This is a template for a simple marketing or informational website. It includes a large callout called a jumbotron
            and three supporting pieces of content. Use it as a starting point to create something more unique.</p>
        <p><a class="btn btn-primary btn-lg" href="#" role="button">Learn more &raquo;</a></p>
    </div>
</div>
<!-- /jumbotron -->

<div class="container">
    <!-- Example row of columns -->
    <div class="row">
        <div class="col-md-4">
            <h2>Heading</h2>
            <p>Donec id elit non mi porta gravida at eget metus. Fusce dapibus, tellus ac cursus commodo, tortor mauris condimentum
                nibh, ut fermentum massa justo sit amet risus. Etiam porta sem malesuada magna mollis euismod. Donec sed
                odio dui.
            </p>
            <p><a class="btn btn-secondary" href="#" role="button">View details &raquo;</a></p>
        </div>
        <div class="col-md-4">
            <h2>Heading</h2>
            <p>Donec id elit non mi porta gravida at eget metus. Fusce dapibus, tellus ac cursus commodo, tortor mauris condimentum
                nibh, ut fermentum massa justo sit amet risus. Etiam porta sem malesuada magna mollis euismod. Donec sed
                odio dui. </p>
            <p><a class="btn btn-secondary" href="#" role="button">View details &raquo;</a></p>
        </div>
        <div class="col-md-4">
            <h2>Heading</h2>
            <p>Donec sed odio dui. Cras justo odio, dapibus ac facilisis in, egestas eget quam. Vestibulum id ligula porta felis
                euismod semper. Fusce dapibus, tellus ac cursus commodo, tortor mauris condimentum nibh, ut fermentum massa
                justo sit amet risus.</p>
            <p><a class="btn btn-secondary" href="#" role="button">View details &raquo;</a></p>
        </div>
    </div>

    <hr>

    <footer>
        <p>&copy; burnmarkGames 2017</p>
    </footer>
</div>
<!-- /container -->


// ============================================================================
// /src/app/demo-modal-child.component.ts

import { Component, ViewChild } from '@angular/core';
import { ModalDirective } from 'ng2-bootstrap/modal';

@Component({
    selector: 'demo-modal-child',
    templateUrl: './demo-modal-child.component.html',
    exportAs: 'child'
})
export class DemoModalChildComponent {
    @ViewChild('childModal') public childModal: ModalDirective;

    public showChildModal(): void {
        console.log('DemoModalChildComponent.showChildModal fired!');
        this.childModal.show();
    }

    public hideChildModal(): void {
        this.childModal.hide();
    }
}


<!-- ========================================================================== -->
<!-- /src/app/demo-modal-child.component.html -->

<div bsModal #childModal="bs-modal" class="modal fade" tabindex="-1" role="dialog"
    aria-labelledby="mySmallModalLabel" aria-hidden="true">
    <div class="modal-dialog modal-lg">
        <div class="modal-content">
            <div class="modal-header">
                <h4 class="modal-title pull-left">Please login...</h4>
                <button type="button" class="close pull-right" aria-label="Close" (click)="hideChildModal()">
          <span aria-hidden="true">&times;</span>
        </button>
            </div>
            <div class="modal-body">
                I am a child modal, opened from parent component!
            </div>
        </div>
    </div>
</div>