Angular modal works in dev mode, but not prod: Cannot resolv

MDBootstrap Pro 7.0.0

Angular 6.1.10

Hi,

I have run into an issue with Angular's injection when creating dynamic modals:

test-component.ts:

import {Component} from '@angular/core';
import {MDBModalRef, MDBModalService} from 'ng-uikit-pro-standard';
import {TestPopupComponent} from './test-popup.component';

@Component({
  selector: 'app-test-component',
  templateUrl: './test.component.html',
})
export class TestComponent {

  private modalRef: MDBModalRef;

  public constructor(private modalService: MDBModalService) {
  }

  public openPopup() {
    this.modalRef = this.modalService.show(TestPopupComponent, {
      class: 'modal-fluid modal-full-height modal-top modal-notify modal-info',
    });
  }

}

test-popup.component.ts:

import {Component} from '@angular/core';
import {MDBModalRef} from 'ng-uikit-pro-standard';

@Component({
  templateUrl: './test-popup.component.html',
})
export class TestPopupComponent {
  constructor(public modalRef: MDBModalRef) {
  }
}

app.module.ts:

@NgModule({
  declarations: [
  ...

TestComponent,
  TestPopupComponent,
],
imports: [
  MDBBootstrapModulesPro.forRoot(),
  ...

],
providers: [MDBSpinningPreloader,
   ...
],
  entryComponents: [
    ...
    TestPopupComponent,
  ]
})

When I run this, I have a problem with the injection on TestComponent:
core.js:1673 ERROR Error: Uncaught (in promise): Error: StaticInjectorError(AppModule)[TooltipDirective -> ElementRef]: 
  StaticInjectorError(Platform: core)[TooltipDirective -> ElementRef]: 
    NullInjectorError: No provider for ElementRef!
Error: StaticInjectorError(AppModule)[TooltipDirective -> ElementRef]: 
  StaticInjectorError(Platform: core)[TooltipDirective -> ElementRef]: 
    NullInjectorError: No provider for ElementRef!

If, instead, I make the object myself, it works fine:

  public constructor(clf: ComponentLoaderFactory, el: ElementRef, v: ViewContainerRef, r: Renderer2) {
    this.modalService = new MDBModalService(clf, el, v, r);
  }


What have I missed?

Thanks!