Hi Sanjog,
Can you try executing the below procedures :
CALL "_SYS_REPO"."GRANT_SCHEMA_PRIVILEGE_ON_ACTIVATED_CONTENT"
('INSERT',' "<Schema_Name>" ','<USERNAME>')
CALL "_SYS_REPO"."GRANT_PRIVILEGE_ON_ACTIVATED_CONTENT"
('INSERT', ' "<Schema_Name>"."<Table_Name>" ', '<USERNAME>');
Regards
Avinash Raju