Hi,

This is a known behavior in Odoo; sequence gaps don't always mean missing records. The most common causes:

1. Cancelled or draft invoices that consumed a sequence number When an invoice is validated, it gets a number. If it's then cancelled and a refund/reset to draft flow was used, the number is consumed but the invoice may not appear in the visible list. Check Accounting > Invoices with filters set to show all states including cancelled.

2. Concurrent transactions / race conditions PostgreSQL sequences are non-transactional by design; if two invoices are created simultaneously and one is rolled back, the sequence number is still consumed. This is expected and actually required by law in some countries (audit trail).

3. Refund/credit notes sharing the same sequence If credit notes use the same sequence as invoices, they consume numbers that look like gaps in the invoice list. Check if credit notes are numbered in the same series.

4. Since August specifically; check if any automated action, scheduled job, or third-party module was activated around that time that creates and cancels draft invoices.

To investigate, run this directly in PostgreSQL:

SELECT name, state, type FROM account_invoice 
WHERE name LIKE 'INV/%' ORDER BY name;

This will reveal any cancelled/draft invoices holding the "missing" numbers.