/clear as block event response doesn't remove items held in hand

When using /clear in an addon as a block event response, only non-selected items in the inventory get removed.

 

How to reproduce:

1. Download the addon
2. Get yourself a couple of blocks with /give @s br:compass_block 64
3. place one down
4. split the blocks up in the inventory
5. click the placed block

see also the video as explanation

Observed behavior: Only blocks, wich aren't in the main hand are removed from the inventory.

Expected behavior: all blocks should be removed