What do you mean that the items never refresh? The only items that are sold by those vendors are the jungle exploration supplies and a decorative vase that come with JA. If you are expecting other things like show up on the stall tables elsewhere in the game (like San Myshuno), then you won't see them. In my game, there are different vendors each visit and they have a slightly different assortment of the JA items, but all sell the same things. The assortment on the table on any given visit to the market does change each visit. Nothing is ever replenished while you are there at the market. That only happens when you leave and come back. If you stay at a rental in the market zone, then things will only change daily in the morning. If you stay in the other zone, they will change every time you visit the market zone.
Hope this helps.
