ezxmlexport checks for exportable nodes via field "published" and not via "modified" - so modified objects are NOT exported.

potential fix:

extension/ezxmlexport/classes/exporter/ezxmlexportexporter.php

if( $latestRunExport != false and $latestRunExport->attribute( 'end_date' ) ) {
$params['AttributeFilter'] = array( array( 'modified', '>=', $latestRunExport->attribute( 'end_date' ) ) );
}

Steps to reproduce

1) edit object
2) start export via cronjob
3) nothing happens if the object was published before but recently only modified