Since v1.2.5 Abantecart have base order_statuses and additional.
for ex.
private $base_statuses = array (
0 => 'incomplete',
1 => 'pending',
2 => 'processing',
3 => 'shipped',
7 => 'canceled',
5 => 'completed',
8 => 'denied',
9 => 'canceled_reversal',
10 => 'failed',
11 => 'refunded',
12 => 'reversed',
13 => 'chargeback',
14 => 'canceled_by_customer');
where key (number) - order_status_id, text - status_text_id for this status.
You should to open database table order_status_ids via phpMyAdmin and compare this list with your data.
Fix you data and clear cache after save.