ngFor doesn't work when at least 1 pipe is added ; Firebase is used in this case.

checkboxfilter.pipe.ts

import { Pipe, PipeTransform, ContentChild } from '@angular/core';
@Pipe({
  name: 'checkboxFilter'
})
export class CheckFilter implements PipeTransform {
  transform(items: any[], filter: any, filterItems: Array < any >, isAnd: boolean): any {
    console.log('Filtering ..');
    if (filter && Array.isArray(items) && filterItems) {
      let filterKeys = Object.keys(filter);
      let checkedItems = filterItems.filter(item => { return item.checked; });
      if (!checkedItems || checkedItems.length === 0) { return items; }
      if (isAnd) {
        return items.filter(item =>
          filterKeys.reduce((acc1, keyName) =>
            (acc1 && checkedItems.reduce((acc2, checkedItem) => acc2 && new RegExp(item[keyName], 'gi').test(checkedItem.value) || checkedItem.value === "", true))
            , true)
        );
      } else {
        return items.filter(item => {
          return filterKeys.some((keyName) => {
            return checkedItems.some((checkedItem) => {
              return new RegExp(item[keyName], 'gi').test(checkedItem.value) || checkedItem.value === "";
            });
          });
        });
      }
    } else {
      return items;
    }
  }
}

filter.pipe.ts

import { Pipe, PipeTransform, ContentChild } from '@angular/core';


@Pipe ({
  name: 'wordFilter',

})

export class FilterPipe implements PipeTransform {

  transform(value, ...args) {
    let resultArray = [];
    if (args.length === 0) {
      resultArray = value;
    } else {
      for (const item of value) {
        if (item.Candidato != null && item.Candidato.match(new RegExp('' + args, 'i')) || item.Text.match(new RegExp('' + args, 'i'))
          || item.Headline.match(new RegExp('' + args, 'i'))) {
          resultArray.push(item);
        }
      }
    }
    return resultArray;
  }
}

filtrotimeline.component.html

<div class="container-fluid linea pad-der">

  <h1>Conoce las Propuestas</h1>
  <div class="col-1">
    <hr>
  </div>
    <h3>Selecciona tus opciones</h3>
  <div class='row'>
    <div class="col-lg-3">
  
      <h5>Candidatos</h5>
      <label for="" *ngFor='let filterItem of filterItems | slice: 0:3; let i = index'>
        <input class='candidato' type="checkbox" name="{{ filterItem.category }}" [value]="filterItem.value" [(ngModel)]="filterItem.checked">{{ filterItem.candidate }}
      </label>

      <h5>Categoría</h5>
      <label for="" *ngFor='let filterItem of filterItems | slice: 3:7'>
        <input class='categoria' type="checkbox" name="{{ filterItem.category }}" [value]="filterItem.value" [(ngModel)]="filterItem.checked">{{ filterItem.value }}
        <br>
      </label>


        <h5>Temática</h5>
        <label for="" *ngFor='let filterItem of filterItems | slice: 7:17'>
          <input class='tema' type="checkbox" name="{{ filterItem.category }}" [value]="filterItem.value" [(ngModel)]="filterItem.checked">{{ filterItem.value }}
          <br>
        </label>


    </div>

    <div class="col-9">
      <input type="text" class="" [(ngModel)]='textSearch'>
      <div id="proposals">
        <div class="search-results scroll" infiniteScroll [infiniteScrollDistance]="1" [infiniteScrollUpDistance]="scrollUpDistance"
          [infiniteScrollThrottle]="throttle" [scrollWindow]="false">
           <table class="" id='appending'>
             <tr *ngFor="let proposal of proposals | wordFilter : textSearch"> 
               <!-- checkboxFilter : checked() | wordFilter : textSearch | -->
                <td class="candidato"> {{proposal.candidato}} </td>
                <td class="categoria"> {{proposal.group}} </td>
                <td class="tema tema-space"> {{ proposal.tema}} </td>
                <td class="headline">{{ proposal.text.headline}} </td>
                <td class="text"> {{ proposal.text.text}} </td>
                <td class="fuente">
                  <a href="{{ proposal.media.url}}"> Leer nota </a>
                </td>
             </tr>

            </table>

        </div>


    </div>
    
  </div>
    
      
</div>

filtrotimeline.component.ts

import { Component, OnInit, ViewEncapsulation, AfterViewInit } from '@angular/core';
import { FormsModule } from '@angular/forms';
import { Http, Response } from '@angular/http';
import { HttpModule } from '@angular/http';
import { InfiniteScrollModule } from 'ngx-infinite-scroll';
import { AngularFireDatabase } from 'angularfire2/database';
import { Observable } from '@firebase/util';


@Component({
  selector: 'app-filtrotimeline',
  templateUrl: './filtrotimeline.component.html',
  styleUrls: ['./filtrotimeline.component.css'],
  encapsulation: ViewEncapsulation.None,
})
export class FiltrotimelineComponent implements OnInit, AfterViewInit {
  events: any;
  proposals: any = [];
  originalProposals: any = [];
  filteredProposals: any = [];
  search = '';

  constructor(private db: AngularFireDatabase) {

  }

  objectKeys = Object.keys;

  filterItems: Array<any> = [
    { candidate: 'Meade', value: 'JAMK', checked: false },
    { candidate: 'Anaya', value: 'RAC', checked: false },
    { candidate: 'AMLO', value: 'AMLO', checked: false },
    { category: 'Propuestas', value: 'Propuestas', checked: false },
    { category: 'Campaña', value: 'Campaña', checked: false },
    { category: 'Actores', value: 'Actores', checked: false },
    { category: 'Entorno', value: 'Entorno', checked: false },
    { theme: 'Administración Pública', value: 'Administración Pública', checked: false },
    { theme: 'Corrupción', value: 'Corrupción', checked: false },
    { theme: 'Desarrollo Económico', value: 'Desarrollo Económico', checked: false },
    { theme: 'Educación', value: 'Educación', checked: false },
    { theme: 'Género', value: 'Género', checked: false },
    { theme: 'Medio Ambiente', value: 'Medio Ambiente', checked: false },
    { theme: 'Política Exterior', value: 'Política Exterior', checked: false },
    { theme: 'Salud', value: 'Salud', checked: false },
    { theme: 'Seguridad', value: 'Seguridad', checked: false },

  ];


  onScroll() {
    if (this.proposals.length < this.originalProposals.length) {
      let len = this.proposals.length;

      for ( let i = len; i <= len + 20; i++) {
        this.proposals.push(this.originalProposals[i]);
      }
    }
  }

  checked() {
    return this.filterItems.filter(item => item.checked);
  }

  searchWord(event: any) {
    console.log(event.target.value);
    let resultArray = [];
    this.search = event.target.value;
    if (this.search.length === 0) {
      resultArray = this.originalProposals;
    } else {
      for (const word of this.originalProposals) {
        if (word.Candidato != null && word.Candidato.match(new RegExp('' + this.search, 'i'))
          || word.Text.match(new RegExp('' + this.search, 'i'))
          || word.Headline.match(new RegExp('' + this.search, 'i'))) {
          resultArray.push(word);
        }
      }
    }
    this.proposals = resultArray.slice(0, 20);

    return [this.proposals, this.search];
  }


  ngOnInit() {
    this.db.object('data').valueChanges()
    .subscribe( response => {this.events = response; this.getData(); } );
  }

  ngAfterViewInit() {
    this.toFilter();
  }

  getData() {
    for (let index in this.events['events']) {
      this.proposals.push(this.events['events'][index]);
    }


  }
}