Whenever a custom table is created as XX01.XX_EMP_DATA; i.e XX01 schema
Then this table should be grant to apps schema
GRANT ALL ON XX_EMP_DATA TO APPS;
GRANT SELECT ON XX_EMP_DATA TO APPS_RO;
above APPS_RO is the production read only and APPS is the schema
Instead of apps an USER_NAME can also be given access to specific user