Can't set group panel grid property

Question

So I am using the following markup to generate a wijmo grid and associated group panel.

<div class="grid" >
  <wj-group-panel
    #group
    [grid]="flex"
    [placeholder]="'Drag columns here to create Groups'">
  </wj-group-panel>
  <wj-flex-grid 
    #flex
    [itemsSource]="gridData"
  >
  </wj-flex-grid>
</div>

I noticed that I was unable to drag anything to the group panel, and upon further digging found that the group.grid property was never getting set. I attempted to set it manually using this.group.grid = this.flex, only to find that even after doing so, console logging the group.grid property yielded undefined.

Is there something I am missing here?