When using select block, the item selected appears in the top part of the inventory

When selecting block in survival, depending on what space in the hotbar you select the block in, the block or item you select appears in either the helmet slot, which replaces the head until updated, the other armour slots or the crafting slots. For example, when selecting a wood plank in hotbar section 6, the wood block is visually in my helmet slot. The item isnt actally there and the item cant be retrieved from the slots.