I can't buy anything because always I get message that the shops are overstocked. What's the problem?

MC version is 1.12.2.
Spigot and plugin are latest.
Here's config.yml https://pastebin.com/pw2q1DRt

Since this is an old issue with very little information I am closing it for now. If you still have problems with version 3.4.0+ of SignShop while running Minecraft 1.13.2+ please open a new issue and provide as much information as you can.