if you are at a store when you right click on items they disappear from the inventory

This is indeed a non-vanilla problem, but this plugin shouldn't be causing it. Have you verified that this happens to vending machines that have not been modified by this plugin? Have you also reproduced the issue while the plugin is unloaded?

For a completely clean test, I suggest you unload the plugin, then spawn a vending machine from f1 console, then see if you can reproduce the issue with that vending machine. If you can reproduce the issue in that case, then it's definitely caused by another plugin. If you cannot reproduce the issue, next try loading the plugin and see if you can reproduce the issue with the same vending machine. Next, edit that vending machine with this plugin, and then see if you can reproduce the issue again.

perfectly true ! It's not the plugin's fault!