Items Deleted when "Thrown"
When performing a specific behaviour that would normally throw an item out of your inventory, the game deletes it instead.

Priority and Severity:
B

Server:
Willow, though I suspect the same for other servers running 1.15.

Steps to Reproduce:
1). Have a full inventory.
2). Drop an item on the floor that cannot merge with another stack in your inventory (for example, if your inv is completely full of cobble, and there is a fence item on the ground).
3). Stand on the item (it should stay on the ground because your inventory is full).
4). Open your inventory.
5). Click on a stack in your inventory (and you should pick up the fence).
6). Keep the stack attached to your mouse, then close your inventory.
7). The stack that was attached to your mouse is now deleted.

Expected Outcome:
Expected outcome is for the items attached to the mouse to drop on the ground once you close your inventory.

Actual Outcome:
Items are deleted.

Proposed Fix:
The bug is either caused by 1.15 server client or one of the server plugins, as it does not replicate in 1.15 singleplayer. Wait for Mojang to fix and simply PSA on discord, or see if the issue is caused by custom code.

Notes:
*This bug will also occur if you place the item in your inventory's crafting area, then close your inventory without a spot for it to return to.

*This bug will also occur if you place an item in a crafting table, then close your inventory. Most likely replicates with other workbenches with temporary inventory (I have not tested).

*This bug will not occur if you click on a stack, then click on the empty space outside of your inventory (it will drop as expected).

*This bug will not occur if you have an empty slot in your inventory for the picked-up stack to occupy.

*This bug will not occur if the item attached to your mouse has another stack in your inventory it can return to once you close out. (For example, if your inventory was full of cobblestone in stacks of 32. Picking up a 32-stack will only merge it with another stack once you close your inventory,making it a stack of 64.)