So, the WebAssist MySQLi Update Record incorrectly inserts itself BEFORE the recordset even if you've selected to use the recordset as the Lookup value for the ID field.
What is the point of the extensions if you constantly have to battle issues like this?
Half a day wasted on this.
EDIT: Can I log this as a bug? There is clearly something wrong with the way the MySQLi behaviour inserts itself into a page.