i just found out, this is a thing. like years later. because I haven't gotten around to doing summerset yet ( i am on third faction storyline)
you patched in jewelry crafting tables to every zone, but then you did not put certification in any zone, but the zone of sumerset
if memory serves, jewelry crafting benches were exclusive to sumerset originally. like the clockwork city unique bench, but later patched into every zone
ZOS stop forcing us to spoil entire chapters of the game, to unlock basic features, like daily writs for a crafting skill we already maxed out.