Changes in Oracle 12.1.0.2 prevents the seed from displaying automatically.
This is not an issue in Oracle 12.1.0.1.
WORKAROUND:
Set Oracle parameter "exclude_seed_cdb_view" to FALSE (default TRUE).
Use "Create from Seed" option and the seed option will be automatically found and displayed.
STATUS:
Waiting for fix in a future version of Toad for Oracle.