Originally posted by jonnin:

Sorry, what is he not showing?
I thought his inventory was totally static the whole game, unless this changed in ML update?

Apparently it has updated; certain items only appear for sale once you defeat certain bosses. Im relatively new to the game, but I was playing for a little bit when Haldor sold everything, and then the Mistlands update took away Thunder Stone and Ymir Flesh. We've since defeated Bonemass and Mader, but Haldor's inventory is still incomplete