After a model is created, generate DDL by bringing up the DDL Script Generation window. Under the "What to Generate" tap select the objects, specifically sequences. In the "Select List" tab choose the specific sequences that need to be included in the DDL script being generated.
Most other settings are set to default. A few other settings not related to sequences maybe set.
The "Generate by Properties 'Generate'" in the "Select List" tab is disabled.
The sequence's specific properties widow correctly displays the SQL in the "SQL Preview" tab and has the "Generate" option in the "General" tab enabled (the "Generate SQL Only" option is disabled).
Everything looks to be set up correctly but the sequence script is still not included in the full DDL script generated for the model.