i suspected user error but user confirm they never did that. otherwise also no - item change history exists for that.
=> i created PR-> PO and DD and SDD is per the planned del time - OK.
=> PR-> PO and i changed the DD a year earlier- system prompt message for DD (delv dte cannot be in past), however it took the SDD a year earlier (past dte)- no history on PO.
In a nutshell all of such PO's seems to have manually created w.r.t PR and not AUTO PO's so user error may be the case but due to no change history it's hard to establish that.
thanks in advance for your advise.