When saved, Table Data is being rendered with multiple tables.
Check the storage format of the affected page. Look at the HTML structure of the table used within Table Data macro, you will be able to see the CSS classes added by xTables add-on.
CauseTable Data macro has a strict format where the it requires a default Confluence table nested within the macro, with one table header and one table body with one row. xTables add-on adds CSS classes into the Confluence table, and this causes the table to break up when being saved.
Remove the said CSS classes via the Confluence Source Editor add-on.
After removing the CSS classes, Table Data macro should be rendering correctly.