When using /give in quick succession while also using items, the items summoned will not appear in the inventory but can still be used/placed.

When the items are taken out of the inventory they will appear again as normal items.

The video below shows that I have made a datapack which when I enable it, it will give me one new smoothstone every tick until I have 5 in my inventory, when I place them they don't reappear but I am still able to use them.

To see the problem, use this datapack, tag a yourself "block" and "Power". Then /trigger block and it will give you the blocks with the issue in question.