CAN NOT expand Angular Material table

I tried for the past 2 weeks to get this code to work. I searched and tried the solution from Philipp Kief which is a solution that I could partly understand. I'm new.

And I also studied these other solutions. Ho Wei Lip 2 and Ho Wei Lip 3

Unfortunately, I'm stuck and I don't know why the table doesn't expand. I don't get an error, but it seems to (click) and MatRipple seems to respond. I also tried, material expansion panel, but it seems off topic. Could someone point me in the right direction? Thank you.

import { Component, OnInit, ViewChild } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import { DataSource } from '@angular/cdk/collections';
import { Incident } from './interface';
import {
  MatSort,
  MatTableDataSource,
  ICON_REGISTRY_PROVIDER,
  MatPaginator
} from '@angular/material';
import {
  animate,
  state,
  style,
  transition,
  trigger
} from '@angular/animations';
import { switchMap, concatMap } from 'rxjs/operators';
import { interval } from 'rxjs';
import { timer } from 'rxjs/observable/timer';

@Component({
  selector: 'app-incident',
  templateUrl: './incident.component.html',
  styleUrls: ['./incident.component.css'],
  animations: [
    trigger('detailExpand', [
      state(
        'collapsed',
        style({ height: '0px', minHeight: '0', visibility: 'hidden' })
      ),
      state('expanded', style({ height: '*', visibility: 'visible' })),
      transition(
        'expanded <=> collapsed',
        animate('225ms cubic-bezier(0.4, 0.0, 0.2, 1)')
      )
    ])
  ]
})
export class IncidentComponent implements OnInit {
  constructor(private http: HttpClient) {}
  @ViewChild(MatSort) sort: MatSort;
  private serviceUrl = 'http://localhost:3001/api-incidents/55';

  FIVE_MINUTES = 5 * 60 * 1000;
  panelOpenState = false;
  incidents: Incident;
  incidentParseArray: any;
  incidents_sortable: any;
  displayedColumns: string[] = [
    // 'statusIcon',
    'incident'
    // 'INCIDENT_TYPE',
    // 'MODIFICATION_DATE',
    // 'prognosisIcon'
  ];
  dataSource = new MatTableDataSource<Incident>(this.incidentParseArray);

  expandedElement: any;
  isExpansionDetailRow = (i: number, row: Object) =>
    row.hasOwnProperty('detailRow')

  ngOnInit() {
    timer(0, this.FIVE_MINUTES).subscribe(() => {
      this.http.get<Incident>(this.serviceUrl).subscribe(response => {
        this.incidents = response;
        const incidentArray = Object.values(this.incidents);
        // console.log('array ===> ', incidentArray);
        this.incidentParseArray = incidentArray.map(
          ({
            INCIDENT_NAME,
            eStatus,
            eSTATUS_COLOR,
            INCIDENT_TYPE,
            ePROGNOSIS,
            ePROGNOSIS_COLOR,
            MODIFICATION_DATE
          }) => {
            const [incident, aux] = INCIDENT_NAME.split(/-\s+/, 2);
            const [status, active] = eStatus.split(/-\s+/, 2);
            const [junk0, statusColor, junk1] = eSTATUS_COLOR.split(/\./, 3);
            const [junk2, prognosisColor, junk3] = ePROGNOSIS_COLOR.split(
              /\./,
              3
            );
            const statusIcon = assignStatusIcon(statusColor);
            const prognosisIcon = assignPrognosisIcon(ePROGNOSIS);
            const prognosisColorText = assignPrognosisColor(prognosisColor);
            const statusColorText = assignStatusColor(statusColor);

            return {
              incident,
              status,
              statusColor,
              statusIcon,
              statusColorText,
              prognosisColor,
              prognosisColorText,
              INCIDENT_TYPE,
              ePROGNOSIS,
              prognosisIcon,
              MODIFICATION_DATE
            };
          }
        );
      });
    });
  }
}

function assignStatusIcon(color) {
  let icon = '';
  if (color === 'gray') {
    icon = 'brightness_1';
  } else if (color === 'green') {
    icon = 'brightness_1';
  } else {
    icon = 'broken_image';
  }
  return icon;
}

function assignStatusColor(color) {
  let pcolor = '';
  if (color === 'gray') {
    pcolor = 'grey-text';
  } else if (color === 'green') {
    pcolor = '#00c853 green-text accent-4';
  } else {
    pcolor = 'black-text';
  }
  return pcolor;
}

function assignPrognosisIcon(str) {
  let icon = '';
  if (str === 'Monitoring') {
    icon = 'remove_red_eye';
  } else if (str === 'Response') {
    icon = 'directions_walk';
  } else {
    icon = 'broken_image';
  }
  return icon;
}

function assignPrognosisColor(color) {
  let pcolor = '';
  if (color === 'grey') {
    pcolor = 'grey-text';
  } else if (color === 'red') {
    pcolor = 'red-text';
  } else {
    pcolor = 'black-text';
  }
  return pcolor;
}

and this is my template.

<mat-table #table [dataSource]="incidentParseArray" matSort class="z-depth-2 table-font-size
    mat-display-10">
    <ng-container matColumnDef="incident">
        <th mat-header-cell *matHeaderCellDef class="table-font-size" [ngClass]="'customWidthClass'">
            INCIDENT </th>
        <td mat-cell *matCellDef="let element" class="table-font-size mat-cell" [ngClass]="'customWidthClass'">
             </td>
    </ng-container>
    <!-- EXPANDED CONTENT  - TEST -->
    <ng-container matColumnDef="expandedDetail">
        <mat-cell *matCellDef="let element">
            The symbol for  is
            TEST TEST TEST
        </mat-cell>
    </ng-container>

    <mat-row *matRowDef="let row; columns: ['expandedDetail']; when: isExpansionDetailRow"
        [@detailExpand]="row.element == expandedElement ? 'expanded' : 'collapsed'"
        style="overflow: hidden">
    </mat-row>


    <mat-header-row *matHeaderRowDef="displayedColumns"></mat-header-row>
    <mat-row mat-row *matRowDef="let row; columns: displayedColumns;"
        matRipple
        class="element-row"
        [class.expanded]="expandedElement == row"
        (click)="expandedElement= row">

    </mat-row>

</mat-table>

from CAN NOT expand Angular Material table