How to detect all changes to input value mdb-auto-completer

Firstly, I need to mention that I use 7.5.4 and I can't upgrade to 8.x since my project is in production and the number of style changes required is overwhelming.

I've created the next mdb-auto-completer shell component I'm going to use in my application (with some debug code included):

import { Component, Input, ViewChild, ElementRef, OnInit } from '@angular/core';
import { Observable, Subject } from 'rxjs';
import { startWith, map } from 'rxjs/operators';
import { MdbAutoCompleterComponent } from 'ng-uikit-pro-standard';

@Component({
  selector: 'app-modal-auto-completer',
  template: `
    <div class="md-form">
      <input #autoCompleteInput
        type="text"
        class="completer-input form-control mdb-autocomplete"
        [ngModel]="autoCompleteValue | async"
        (change)="valueChanged($event)"
        (ngModelChange)="autoCompleteValue.next($event); log($event)"
        [mdbAutoCompleter]="autoCompleter"
        placeholder="{{placeholder}}"
      />
      <mdb-auto-completer #autoCompleter="mdbAutoCompleter" textNoResults="{{emptyResult}}">
        <mdb-option *ngFor="let option of optionList | async" [value]="option">
          {{option}}
        </mdb-option>
      </mdb-auto-completer>
    </div>
  `,
  styles: []
})
export class ModalAutoCompleterComponent implements OnInit {
  @ViewChild("autoCompleter") autoCompleter: MdbAutoCompleterComponent;
  @ViewChild("autoCompleteInput") autoCompleteInput: ElementRef;

  @Input() placeholder: string;
  @Input() emptyResult = "No results found";
  @Input() selector: (search: string) => string[];

  autoCompleteValue = new Subject();
  optionList: Observable<string[]>;

  constructor() { }

  ngOnInit() {
    this.optionList = this.autoCompleteValue.pipe(
      startWith(''),
      map((value: string) => this.selector(value))
    );
  }

  valueChanged(event: any) {
    console.log("Changed", event);
  }

  log(event: any) {
    console.log("Event", event);
    console.log("Value", this.autoCompleter.getSelectedItem());
    console.log("Input value", this.autoCompleteInput.nativeElement.value);
  }
}

So I have an input "selector" function that allows me to reuse the component in different places of my application and still hide all pipes, subjects and object things. I was really surprised that for some reason (ngModelChange) is never triggered for the main workflow with the auto completer, that is, to select some option from the list. Also (change) is never triggered at all. What then is way to detect the change of the input value (originated from any source - selection of an option or from manual input)? Using subscriptions for the case is just nonsense since it's expected that the component should work the same as any ordinary input -> it's passed a pointer to some data -> it changes the data on input changes -> at some point all data is submitted without any manual calls to the auto completer or checking it's value.

Thank you in advance for the reply.