I can't set up more than 12 items but could 16... Did I do something wrong in my life?
Once you put 12 items, you just continue adding more and it automatically adds a small scrollbar.
Are doing that? If not, then what's the error you're getting?
Navigator, tools, guides and much more!
Visit us at: https://thepiratescove.org
after playing/experimenting a bit and looking at your picture I think you may be a victim of LAG and not all data loading - try a game re-start or go through a portal, then re-set up booth.
but just in case....................................
What you should be doing is
1) open sales interface : choose character or ship tabs on interface, then equipment, article etc tabs... then click the item you want to sell (from the 4x9 slots equipment, article etc... at the bottom of the interface)
2) screen 2 pops up and put in price and possibly amount (name and item info comes up automatically) - then click yes
3) after all 12 slots are full click the 13th item you want to sell.. and the scroll will appear
as in the 1st picture you have to scroll to see 13th item with a new line of empty slots.
to take an item off of sale - right click the item in the 2x6 slots area at the top.
to edit the sales information left click the item in the 2x6 slots area at the top.
Clicking a blank space at top only lets your enter items you want to PURCHASE not SELL!
Notice name and information does not automatically come up (see image 3 below) ... and as you noticed you can only add 12 by doing it this way (unless you add something to sell (slot 13), add a purchase (slot 14) then remove item for sale)
That screen is only used when you want to buy items... which almost nobody does because no one in game will know you want to buy stuff unless they happen to look at your booth or by chance click "purchase inquiry" in the click to trade interface. Most people just announce in public they want to buy something.
*sales and purchase items look a bit different though see picture 4 for a purchase item...
this is why I think the above is a victim of lag and not all data being loaded.
Purchase items show as a wood box.... with green writing "To Be..." sales writing is blue "To Be..."
if you click empty slot square at top you get: