Table exists in store procedure while used in select but not when used in insert statement

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Oracle

When table another_schema.Dw_table used in store procedure only to fetch the data its working there but when I used in Insert statement it throws PL/SQL: ORA-00942 table or view does not exist.

What I have tried:

create or replace procedure tpk.sp_Test_proc
IS
   err_code      NUMBER;
   err_msg       VARCHAR (500);
   v_tbl_cnt     NUMBER;
   v_tbl_valid   NUMBER;
Begin
SELECT COUNT(*) INTO v_tbl_cnt  FROM USER_TABLES 
  WHERE TABLE_NAME IN (UPPER('Tbl1'),UPPER('tbl2'),UPPER('tbl3'));

IF(v_tbl_cnt =3) THEN

EXECUTE IMMEDIATE 'TRUNCATE TABLE Tbl1';
    EXECUTE IMMEDIATE 'TRUNCATE TABLE Tbl2'; 
    EXECUTE IMMEDIATE 'TRUNCATE TABLE Tbl3';

    EXECUTE IMMEDIATE 'DROP TABLE Tbl1';
    EXECUTE IMMEDIATE 'DROP TABLE Tbl2'; 
    EXECUTE IMMEDIATE 'DROP TABLE Tbl3';

EXECUTE IMMEDIATE
    'CREATE global temporary TABLE tbl1
    ( Id Integer... )'

Insert into tbl1
Select * from another_schema.Dw_table /* In this line it throws error Table does not exist */
end if;
end;