Items disappear when inventory is closed instead of being added back to the inventory.

When the player inventory is closed, the items which are on the cursor are not added back to the inventory as it does in 1.16 spigot and 1.17 vanilla as well.
Steps to reproduce:
1. Open the player inventory.

2. Click on an item in the inventory such that it is on the cursor.

3. Close the inventory by pressing 'E' or 'Esc'.