Created attachment 155430 [details] Database and hsqldb.jar of HSQLDB 2.5. Extract and change connection for test. This special bug appears with the external HSQLDB since 2.4.0. Have tested it also with 2.5.0 - same behaviour. In the attached database is a query which only will work in direct SQL. It links two queries with the same fields by UNION: SELECT "Nachname", "Geburtstag" FROM "Teilnehmer" WHERE YEAR("Geburtstag")<'1980' UNION SELECT "Nachname", "Geburtstag" FROM "Teilnehmer" WHERE YEAR("Geburtstag")>'2000' The query could be started in the GUI with direct SQL. No error appears, no rows will be shown. The query could be started in Tools > SQL. The rows will be shown when the checkbox for showing the output will be pressed. Expected behaviour: Query-GUI should show all output which will be shown as output through Tools > SQL.
Unfortunately, can't test on macOS.
Two additional hints: The path to the external hsqldb.jar is stored in the macro "Start", which is executed after database file has been opened. Creating a view of the query will show the same content as executing through Tools → SQL. When trying to edit the view and running the view in the editor the content isn't shown.