Bukkit

Whenever using a double chest, as soon as a block is placed above half of the chest, the sign only uses items from the half of the chest that the sign is placed on.

Can you please provide the requested information from the template? (plugin and server version as well as the log and config file) Also a picture of the setup of your shop would be good.

It's with all versions used, I used the most recent, on a 1.14.4 server with no other plugins other than Vault and Essentials, config file is default and the shop setup is literally just a double chest, 1 single shop sign on it, and any block placed on either side of the chest other.

Unfortunately it seems like this is an issue with how the Bukkit API is implemented for double chest inventories (it uses an NMS method to detect whether or not it is a double chest or not and that does not return it as a double chest if there is a block on one side) and I don't really know a good way right now of working around that in the plugin itself and it's something that should be fixed in the server itself rather than the plugin. (Of course that would require you to update when a fix is available or backport it yourself) I might look into that when I find the time and at least open an issue in the Spigot jira once I've investigated it a bit further.

I'm facing the same problem. Are there any news regarding the Bukkit API bug?

Chest-Shop 3.10.2-SNAPSHOT (build 178)

Paper 1.15.2 - 282