Summary:
When running the /clear command on a player to remove all of their items, they're still able to prevent some items from being cleared by putting them into the crafting grid in their inventory.

This bug also existed in Java Edition and was fixed in 20w07a: MC-75328.

Steps to Reproduce:

1. Place a command block
2. Type the following command into the command block: /clear @p
3. Place a button that activates the command block after some time (e.g. by using repeaters)
4. Press the button
5. Open your inventory and put an item into the crafting grid
6. Wait for the /clear command to run

Observed Results:
The item in the crafting grid is not cleared.

Expected Results:
The item should be cleared.

Video:
Minecraft 2022-02-06 08-26-57.mp4