Background

When the player is rearranging their inventory, they can pick up an item onto the cursor.

The /clear command, when given a maxCount of zero, doesn't actually clear any items, but instead counts how many items the player has.

Using /clear in this way includes items that are being held by the cursor.

The bug

The new hasitem selector argument does not include items that are being held by the cursor. Therefore, behavior achievable with /clear cannot be replicated using this feature. It is critically important that all use cases of /clear are replicable, because Bedrock is still using the old outdated 1.12-style /execute command that makes it impossible to use /clear in functions.

How to reproduce

Create a repeating command block with this command:

/give @a[hasitem={item=apple,quantity=0}] diamond

Power it and add an apple to your inventory. Now open your inventory and pick up the apple.
Expected behavior
Player doesn't get anymore diamonds, since you have an apple
Actual behavior
Player continues getting diamonds so long as the apple is on the cursor

Notes
You'll also probably notice annoying ghost apples that appear when you try to place it down. Please fix that too