With a full inventory, breaking down more than 7 storage blocks causes the extra items to be deleted instead of placed into inventory.

To reproduce:

1) Grab 8 iron (emerald, gold, diamond, slime...) blocks
2) Fill up the rest of your inventory with other junk (not those blocks, and not the item that the block breaks down into)
3) Put the 8+ blocks into the crafting grid. There should be 1 empty space in your inventory
4) Shift+click to craft all 8 blocks at once. Notice there are 64 ingots in the old empty slot, with the other 8 missing