I believe there was a stale extension installed that was causing the following error when attempting to insert sitemaps and inserting new content.

tx_auxnewsmailer_newsletter
2: SQL error: 'Unknown column 'tx_auxnewsmailer_newsletter' in 'field list'' (tt_content:NEW44ce1b0a63563)

Removing and re-installing the extension auxnewsmailer resolved the problem.