Table Cell Element is not currently exporting the contents on export

[velara3]

When exporting a Table Cell Element, the contents of the cell are not exported. For example, a table cell with a paragraph that says "Hello world" should export the following:

<table>
  <tr>
    <td><p>Hello World</p></td>
  </tr>
</table>

Or:

<table>
  <tr>
    <td><TextFlow><p>Hello World</p></TextFlow></td>
  </tr>
</table>

but currently it is only exporting:

<table>
  <tr>
    <td />
  </tr>
</table>

Steps to reproduce:

1. Open Table Explorer
2. Click Add Editable Table
3. Type content into the first cell
4. Check the Text Flow output text area

It should be showing the contents of the cell but it currently does not.