From SQL Loader, when reaching the "Select the destination table and columns and specify their load parameters" page, try to add a table and select the Load method (e.g. INSERT). After pressing OK, the value of the Load Method on the grid shows APPEND instead. Click edit and modify the load method to APPEND | OK | then the grid shows INSERT instead.
Product defect.
WORKAROUND
Change the Load Method from the table grid to the correct value.
STATUS
Waiting for fix in a future release of Toad for Oracle.