(I can't find the option to fix this, but my skin does not show me who is in the group if they're not in the same zone. Ugh. PITA when someone dies and they're like, 'rez me', and I can't find them or anything.)
As long as they are still in your group and haven't come back into the zone, you can still target their corpse with the correct F2-F6 key. I bet that works even when you can't see the names.