WORKAROUND
Use CAST in the cross-query to workaround the problem. Example:
Original:SELECT EMPNO
FROM `oracle_connection`.SCOTT.EMPLOYEE;
Workaround:
SELECT cast (B.EMPNO as varchar2(120))
FROM `oracle_connection`.SCOTT.EMPLOYEE B;
STATUS
Awaiting on a fix in a future version of Toad Data Point/Toad Intelligence Central.