Preliminaries:

• Shopkeepers version: 2.9.2
• Spigot version: This server is running Paper version git-Paper-143 (MC: 1.15.2) (Implementing API version 1.15.2-R0.1-SNAPSHOT)`

• I have checked that my issue/question does not get answered by:
  • The documentation.
  • The FAQ.
  • The Known Issues.
• I have checked all open and closed issues, but none seems to fit my issue/question.

Reproduction on a fresh and up-to-date Spigot server:

I was able to reproduce my issue on a freshly setup and up-to-date Spigot server (currently Paper version git-Paper-143) with the latest version of Shopkeepers (currently 2.9.2)

The issue:

Provide a detailed description of your problem and add as much information as possible which could help reproducing the issue.

Include:
When we create a new trade into a shopkeppeur.
The moment where we select a item, we select one or a stack and when we click into the case for define this item top sell or buy, us hand was clear.

sorry it s my first issu ^^'

Maybe some other plugin is interfering.
Can you try to:

• Try in on a Spigot server instead of Paper. Paper has some internal differences. Trying it on a fresh and up-to-date Spigot server ensures that these are not the problem here.
• Try it without other plugins. If it works then (which I assume..), try to figure out which other plugin is causing this by adding them step by step. Also, please post your plugins list.

Okay i try to create a new serveur ^^' for test

The problem not come to the plugins .. with spigot only he work

I can't reproduce the same error. On my server , my player can create personalize trade, but in spigot only, i can only trade with emerald ._. ...

The problem not come to the plugins .. with spigot only he work

I am not completely sure I understand: Were you able to confirm that the issue is some other plugin interfering? If that is the case, the next step is to find out which plugin is causing the issue.
What you can do to speed up the search instead of trying one plugin after the other: Add half of the other plugins back. If the issue occurs, remove half of those plugins and so on. If the issue does not occur, try with the other half of the plugins.

I can't reproduce the same error. On my server , my player can create personalize trade, but in spigot only, i can only trade with emerald ._. ...

You might be using different shop types on your server then. There are: Admins shops, selling shops, buying shops, book shops and trading shops. The selling, buying and book shops use emeralds as currency. The trading and admin shops can trade any items.

Okay, after long research, the bug comes from the RecompenseVote. A plugin created by a old player who have quit the team few days ago .. bad luck for us ^^'

The plugin:
https://github.com/la-taverne-mc/RecompensesVote

More than found the problem in this plugin...but if you know the solution i take it! x'D
Thank you for you help ! Sorry for the lost time ^^"

It seems like this plugin is cancelling inventory click events for specific types of items, and forcefully un-canceling it for all other types of items: https://github.com/la-taverne-mc/RecompensesVote/blob/master/src/main/java/me/lataverne/recompensesvote/listeners/MiscellaneousListeners.java#L84
I am not completely sure how this results in the disappearing of the item, but I am glad that you were able to figure out which plugins was causing this!

Hi, thank you for your help, i worked this 3 days to edit a plungin and Now i can edit, and create the .jar ! xD

I wondered if it existed an function to a InventoryClickEvent that can test if an inventory of shopkeepers?

You could check if the inventory is instanceof MerchantInventory (this applies to regular villager trading menus as well though).

Thank you very much, i have solved the bug! ☺