If SYS schema is not entered with DBMS_SESSION (SYS.DBMS_SESSION), then Toad Insight pick list is not displayed in Editor. This behavior has changed since the upgrade from version 9.5.
1. Select View | Toad Options menu option
2. Select Editor | Code Assist from the left-side tree
3. Under Toad Insight Objects list, check Public Synonyms check box and hit OK