SLA accounting doesn't use the associated accounting derivation rules for several cases

Hi,

We have an issue with SLA for accounting purchase invoices:

    We use a custom derivation rule to have a value of the natural account segment, this rule is used since 2014 with no problem, but since 3 months we don't have the desired value for several cases. We didn't make any changes Payables accounting method, rule of associated custom sources or related plsql functions.

   To diagnostic the issue , a copy of the Production instance of May-2019 has been restored and then we posted the same events with issue in the actual instance, 

the result of the posting in ths instance( clone of PROD) is the desired one and not the same that was accounted in the actual PROD.