Hide mat-rows in mat-table when data is loading
So the "trick" was to use [hidden]
<tr mat-row *matRowDef="let row; columns: displayedColumns;" [hidden]="isLoading"></tr>
However I didn't end up using this solution as it made the table "jumpy". Instead I opted to put a spinner in the table footer.
Can't use two structural directives on one element. use ng-container
<ng-container *ngIf="!isLoading">
<tr mat-row *matRowDef="let row; columns: displayedColumns;"></tr>
<ng-container>