Answer
Check specifically whether execute permission on the custom function/package has been granted to the IFSINFO database user — IAL queries execute under IFSINFO's own database session, which is a separate permission context from the one used for Lobby elements or Quick Reports, so 'permissions have been granted' generally isn't enough if IFSINFO specifically wasn't included. On environments where it applies, Database_SYS.Grant_All_Objects_Ial('IFSINFO') is the procedure used to grant IFSINFO the necessary access to custom database objects for IAL use.