Data cell is marked as a header cell
Data cells MUST NOT be marked as header cells.
People who are blind cannot see the organizational structure of a table with data arranged in rows and columns with corresponding header cells. In order for screen reader users to understand the logical relationships of data arranged in a table, tables need HTML markup that indicates header cells and data cells and defines their relationship. When tables are marked correctly, screen reader users are able to navigate data tables from cell to cell, in a multi-directional way (up, down, right, left), much like navigating a spreadsheet. As they move from cell to cell, screen readers will read the associated header labels.
Fix this issue by doing ONE of the following:
Change the <th> to a <td>.
Remove the columnheader or rowheader attribute.