A small change to the function MakeView_LV_MSGSVCINIT in ..\common30\utils\langsetup.prg solves the problem. I'll post this in case someone else needs it.

ORIGINAL CODE:
CREATE SQL VIEW "LV_MSGSVCINIT" ;
AS SELECT * from msgsvc where ilangid = vp_iLangID OR (ilangid = 0 AND ckey NOT IN (SELECT ckey FROM msgsvc WHERE ilangid = vp_iLangID))

CHANGED TO:
CREATE SQL VIEW "LV_MSGSVCINIT" ;
AS SELECT * from msgsvc where (ilangid = ?vp_iLangID) OR (ilangid=0 AND ckey NOT IN (SELECT ckey FROM msgsvc WHERE ilangid = ?vp_iLangID))