User is Not Getting Email for Oracle Notificati​on Such As Approval Kind of Mail.

Check notification_preference is ENABLED or DISABLED wf_local_roles for
that user?  If Disabled then run the below update

UPDATE WF_LOCAL_ROLES
SET STATUS ='INACTIVE' ,EXPIRATION_DATE = (SYSDATE-1)
WHERE NAME LIKE '&user_name'
AND PARENT_ORIG_SYSTEM ='WF_LOCAL_USERS'
AND NOTIFICATION_PREFERENCE ='DISABLED';


After that issue a commit and run the below program.
Synchronize WF LOCAL tables