Some table headers don't scroll on pages with tables nested in tables

Issue Summary

When a table with nested table header is added to the page, it prevents other tables from initialising properly. The sticky table header element appears in the DOM but does not move when scrolling the page.

Steps to Reproduce

1. Step 1 Add a page with a table nested inside another table's header row
2. Step 2 add another table that should scroll, to the page.

Expected Results

The second table's header should scroll down with the page

Actual Results

The regular table's header doesn't scroll

Workaround

Remove the nested table from the page