Dear all,
We have identified the issue. There was a 3rd party library update meanwhile, therefore we have to use it differently. Please use following instruction as a workaround:
From your MDB  package (/typescript/index.ts or /node_modules/ng-mdb-pro/index.ts) remove or comment out ToastModule from following lines:

49:

// export {

// ToastComponent, ToastContainerDirective, ToastContainerModule, ToastInjector, ToastPackage, ToastRef, ToastIconClasses,

// ToastModule, ToastService, GlobalConfig, IndividualConfig, Overlay, OVERLAY_PROVIDERS, OverlayContainer, OverlayRef

// } from './alerts/';
103:
const MODULES = [

...

110: //ToastModule,

...

];
122:
@NgModule({

imports: [
...
130: //ToastModule.forRoot(),
...
],

exports:MODULES,

providers: [

],

schemas: [ NO_ERRORS_SCHEMA ]

})

export class MDBRootModulePro {

}

In your app.module.ts except for importing MDB and MDB PRO, import ToastModule from Typescript:
import { ToastModule } from './typescripts/pro/alerts';
or node_module
import { ToastModule } from 'ng-mdb-pro/pro/alerts';
and add it to imports:

imports: [
...
ToastModule.forRoot(),
...
],

Now you can import MDB in any other module without having an issue with Toastr, however, please do not import Toast again. If you want to use it other modules, simply import Service:

import {ToastService} from '../../typescripts/pro/alerts' 

add it to constructor:

constructor(
...
private toast: ToastService
...
) { }

and use it i.e.:

ngOnInit() {

this.initForm();

setTimeout(

() => this.toast.info("It works!")

);

}

Hey,

I'm waiting too for a solution.