Two missing record from this query

Despite the fact that you're technically in the wrong forum, this is a logic error.

Because of the "MAX" statement, you'll only get one match with that t1.LMDTM1 = (...) comparison.

Of course, returning more than one row on that subquery would lead to other errors.

I would attempt to replace your equality and subquery with a join, see if that helps.

SELECT 
    '20'||SUBSTR(CAST(T1.LMDTM1 as VarCHar(15)), 2, 6) as Date, 
    T1.LMFSTM as Status,
    T1.LMREF1 as CustPO, 
    TRIM(T1.LMREF1) ||'-'||TRIM(T1.LMREF2) as Key,
    T1.LMREF2 as Order, 
    T1.LMREF3 as GUID
FROM EXTSYSFCC.EXLLMQLD T1
JOIN EXTSYSFCC.EXLLMQLD T2
    ON t2.LMREF2 = t1.LMREF2
WHERE 
    t1.LMTPC1 = 'ABC' 
AND 
    t1.LMMSID = '123'
AND 
    t1.LMDTM1 = t2.LMDTM1;

In the future, Oracle PL SQL related questions should be asked at their community forum, in order to improve your chances for relevant replies.
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