Personal and Server-Owned Skyblock Shops are broken.

Whenever I (Tedra) try to make a Personal-Privately owned Shop on my Skyblock Item the sign doesn't seem to work for the player that is wishing to buy the item. Currently, instead of allowing the player to buy the item in the chest of which has the Shop Sign command thing displayed on it, it either says:

"Out of Stock!"
or
"Item Cannot be Sold"

It is weird as there is also the thing of where when you put the name of the block, for EXAMPLE, Sugarcane, it will give a categorized number such as 338 or something. I do not know if this causes the item to not be sold or display Out of Stock despite there being items inside of it.
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Another thing to mention is that in the Server Owned Shop, that the items are oddly not displaying in the item frames in the big air-ship shop, while also allowing me to not be able to buy any of the items inside. Along with how I buy things from the Work In Progress shop by clicking on the chest to get to the item, it just displays "Sorry! But this cannot be Opened!" while still allowing me to open it and buy it...

Is this a Siggi Problem? Its been going on for quite some time. I desire the joy of buying an item and selling an item from a shop.

Edit: Jerio says this is a Siggi thing. I would like to know if anybody else is having this issue too!

for the Skyblock chest shop, its because the shop plugin is based on chests and the world guard is overaggressive and does not allow you to open chests. for the sign shops in the ship, I'm not sure whats causing that cause they worked for me, and the item frames are empty because while jer/siggi/whoever made the shop, they removed them as they added them in the chest shops.