I was messing with item sorters,hoppers and came along weird bug that emeralds act different then glowstone,diamond,iron or lapis maybe even more (these were the only ones that i tested). It seems like hoppers wont detect emerald unless it is placed directly on top of it, other wise it will just skip it and go to misc chest. There is a way to fix this but it would require way more resources and would be bigger. This is design from ac-tennis, just simplified, and bugged. - vilhardo