El problema en su consulta es que la cláusula where se aplicará solo al nivel 1 y no más.
Prueba esto usando una tabla anidada:
WITH xtable AS (
SELECT 1 ID, '116,117,169,170,173,175,9015,44008,44367,44446,45081,45083,46779,47161,47222' AGT FROM DUAL
UNION ALL
SELECT 2 ID, '456,789' AGT FROM DUAL
UNION ALL
SELECT 3 ID, '116,117,169,170,173,175,9015,44008,44367,44446,45081,45083,46779,47161' AGT FROM DUAL
)
select regexp_substr(x.AGT,'[^,]+', 1, t.column_value) agt
from xtable x cross join table(
cast(
multiset(
select level
from dual
connect by level <= regexp_count(x.AGT,',') + 1
)as sys.odcinumberlist
)
) t
where x.id = 3;
Es una consulta de propósito general que puede usar incluso sin la cláusula where si desea convertirlos todos a la vez.
En Oracle 12c+, puede usar OUTER APPLY
para lograr el mismo efecto y una sintaxis más simple:
WITH xtable AS (
SELECT 1 ID, '116,117,169,170,173,175,9015,44008,44367,44446,45081,45083,46779,47161,47222' AGT FROM DUAL
UNION ALL
SELECT 2 ID, '456,789' AGT FROM DUAL
UNION ALL
SELECT 3 ID, '116,117,169,170,173,175,9015,44008,44367,44446,45081,45083,46779,47161' AGT FROM DUAL
)
select regexp_substr(x.AGT,'[^,]+', 1, t.n) agt
from xtable x
outer apply (
select level n
from dual
connect by level <= regexp_count(x.AGT,',') + 1
) t
where x.id = 3;