Im a bit baffled, im retrieving data from my Spring Boot back end to populate into an angular material table but for whatever reason the rows do not display until i use sorting or change pagination. I get the sense im missing something obvious, any help is appreciated.

datasource.ts

import { DataSource } from '@angular/cdk/collections';
import { MatPaginator } from '@angular/material/paginator';
import { MatSort } from '@angular/material/sort';
import { map } from 'rxjs/operators';
import { Observable, of as observableOf, merge } from 'rxjs';
import { ParkingService } from 'src/app/services/parking.service';

// TODO: Replace this with your own data model type
export interface ParkingBuildingTableItem {
  building_name: string;
  postcode: string;
  owner_name: string;
}

// TODO: replace this with real data from your application
const EXAMPLE_DATA: ParkingBuildingTableItem[] = [
  //   { building_name: 'Rohanhaven', postcode: 'SA1 6BS', owner_name: 'Nikolaus, Buckridge and Marvin' },
  //   { building_name: 'Port Garfield', postcode: 'SA1 6BS', owner_name: 'MacGyver, Schneider and Bosco' },
  //   { building_name: 'Port Loveside', postcode: 'SA1 6BS', owner_name: 'Considine, Schimmel and Abernathy' },
];



/**
 * Data source for the ParkingBuildingTable view. This class should
 * encapsulate all logic for fetching and manipulating the displayed data
 * (including sorting, pagination, and filtering).
 */
export class ParkingBuildingTableDataSource extends DataSource<ParkingBuildingTableItem> {
  data: ParkingBuildingTableItem[] = []
  paginator: MatPaginator | undefined;
  sort: MatSort | undefined;

  constructor(private parkingService: ParkingService) {
    super();
    this.parkingService.getBuildings().subscribe((x) => {
      this.data = x;
      console.log(this.data);
    });
  }

  /**
   * Connect this data source to the table. The table will only update when
   * the returned stream emits new items.
   * @returns A stream of the items to be rendered.
   */
  connect(): Observable<ParkingBuildingTableItem[]> {
    if (this.paginator && this.sort) {
      // Combine everything that affects the rendered data into one update
      // stream for the data-table to consume.
      return merge(observableOf(this.data), this.paginator.page, this.sort.sortChange)
        .pipe(map(() => {
          return this.getPagedData(this.getSortedData([...this.data]));
        }));
    } else {
      throw Error('Please set the paginator and sort on the data source before connecting.');
    }
  }

  /**
   *  Called when the table is being destroyed. Use this function, to clean up
   * any open connections or free any held resources that were set up during connect.
   */
  disconnect(): void { }

  /**
   * Paginate the data (client-side). If you're using server-side pagination,
   * this would be replaced by requesting the appropriate data from the server.
   */
  private getPagedData(data: ParkingBuildingTableItem[]): ParkingBuildingTableItem[] {
    if (this.paginator) {
      const startIndex = this.paginator.pageIndex * this.paginator.pageSize;
      return data.splice(startIndex, this.paginator.pageSize);
    } else {
      return data;
    }
  }

  /**
   * Sort the data (client-side). If you're using server-side sorting,
   * this would be replaced by requesting the appropriate data from the server.
   */
  private getSortedData(data: ParkingBuildingTableItem[]): ParkingBuildingTableItem[] {
    if (!this.sort || !this.sort.active || this.sort.direction === '') {
      return data;
    }

    return data.sort((a, b) => {
      const isAsc = this.sort?.direction === 'asc';
      switch (this.sort?.active) {
        case 'building_name': return compare(a.building_name, b.building_name, isAsc);
        case 'postcode': return compare(a.postcode, b.postcode, isAsc);
        case 'owner_name': return compare(a.owner_name, b.owner_name, isAsc);
        default: return 0;
      }
    });
  }
}

/** Simple sort comparator for example ID/Name columns (for client-side sorting). */
function compare(a: string | number, b: string | number, isAsc: boolean): number {
  return (a < b ? -1 : 1) * (isAsc ? 1 : -1);
}

component.ts

import { AfterViewInit, Component, ViewChild } from '@angular/core';
import { MatPaginator } from '@angular/material/paginator';
import { MatSort } from '@angular/material/sort';
import { MatTable } from '@angular/material/table';
import { ParkingBuildingTableDataSource, ParkingBuildingTableItem } from './parking-building-table-datasource';
import { ParkingService } from 'src/app/services/parking.service';

@Component({
  selector: 'app-parking-building-table',
  templateUrl: './parking-building-table.component.html',
  styleUrls: ['./parking-building-table.component.scss']
})
export class ParkingBuildingTableComponent implements AfterViewInit {
  @ViewChild(MatPaginator) paginator!: MatPaginator;
  @ViewChild(MatSort) sort!: MatSort;
  @ViewChild(MatTable) table!: MatTable<ParkingBuildingTableItem>;
  dataSource: ParkingBuildingTableDataSource;

  /** Columns displayed in the table. Columns IDs can be added, removed, or reordered. */
  displayedColumns = ['building_name', 'postcode', 'owner_name'];

  constructor(parkingService: ParkingService) {
    this.dataSource = new ParkingBuildingTableDataSource(parkingService);
  }

  ngAfterViewInit(): void {
    this.dataSource.paginator = this.paginator;
    this.dataSource.sort = this.sort;
    this.table.dataSource = this.dataSource;
  }
}

The HTML

<div class="mat-elevation-z8 data-table">
  <table mat-table class="full-width-table" matSort aria-label="Elements">
    <!-- Owner Column -->
    <ng-container matColumnDef="owner_name">
      <th mat-header-cell *matHeaderCellDef mat-sort-header>Owner</th>
      <td mat-cell *matCellDef="let row">{{row.owner_name}}</td>
    </ng-container>

    <!-- Postcode Column -->
    <ng-container matColumnDef="postcode">
      <th mat-header-cell *matHeaderCellDef mat-sort-header>Postcode</th>
      <td mat-cell *matCellDef="let row">{{row.postcode}}</td>
    </ng-container>

    <!-- Building Name Column -->
    <ng-container matColumnDef="building_name">
      <th mat-header-cell *matHeaderCellDef mat-sort-header>Building Name</th>
      <td mat-cell *matCellDef="let row">{{row.building_name}}</td>
    </ng-container>

    <tr mat-header-row *matHeaderRowDef="displayedColumns"></tr>
    <tr mat-row *matRowDef="let row; columns: displayedColumns;"></tr>
  </table>

  <mat-paginator #paginator [length]="dataSource?.data?.length" [pageIndex]="0" [pageSize]="10"
    [pageSizeOptions]="[5, 10, 20]" aria-label="Select page">
  </mat-paginator>
</div>

Before i sort or change pagnation

After i sort or change pagnation

Snapshot of the console