Items being placed on armor slots (/invsee issue)

[YellowZaki]

Information

Full output of /ess version:

Server log: Anything related to essentials and no exceptions.

EssentialsX config: Tested with default config.

Details

Description

When using /invsee , if you move an item from their inventory to yours, sometimes the item is placed on the armours slots.

I've also tested on a fresh server with no plugins, just Essentials, and it happens too.

Steps to reproduce

1. Use /invsee
2. opens their inventory
3. You move an item of their inventory to yours several times until the item is placed on armour slots.

Expected behavior

No bugs.

Screenshots

Video: https://www.youtube.com/watch?v=46IOLRZDMFo&feature=youtu.be

[Chew]

Duplicate of #3065
Upstream issue still