Database | Export | Export DDL Output file name converts to lower case name.
Database | Export | Export DDL Output file name does not retain upper case letters as entered. As a result, file name is stored as lower case letters.
The "Lowercase filenames" checkbox is checked and disabled since "Single file" is selected,
WORKAROUND: 1. Select any of the "One file..." Output options on the left which will enable "Lowercase filenames" checkbox 2. Uncheck "Lowercase filenames" checkbox and select "Single file" option again
STATUS: Waiting for fix to be released in a future version of Toad for Oracle.