Document Number in journals is null and sequence numbering settings have never changed

Hello Oracle Community,

We are having an issue with Document Number in journals is null. We are looking for the root cause of the issue without success. We do not understand what is different now because sequence numbering settings have never changed, no settings related to this has changed.

In this query, some headers are with Document Number and others not.

select * from apps.gl_je_headers a

where 1=1

and   ledger_id = 19285

and   created_by = 458277

and   period_name = 'APR-19'

order by je_header_id desc

Thank you very much for any insight that you can provide me,

Best Regards