>> If data is coming from backend but not displayed in UI:-
1. ask for get api and find the function for it in service file and replace it
 eg> 
  getPortalUserListForFilter(role, orgId) {
    const API_URL = `${this.env.apiUrl}/Organisations/${orgId}/OrganisationUsersByRoleId?roleIds=1`;
    return this.httpClient
      .get(API_URL)
      .map((data: { Data: { Users: [] }; Status: string }) => data)
      .catch((error) => Observable.throw(error));
  }

2. Replace the variable name in html file using {{ arrayname.variableNameusedInEach}} eg> {{ user.DisplayName }}
3. Change value field in html
<option *ngFor="let user of portalUsers" [value]="user.UserId">
            {{ user.DisplayName }}
          </option>
check if value is mapping or not else undefined logs aaega