Not sure if this really even is a bug at all, but it still seems quite important to bring up,
With torches, they only break blocks like sand if they're place on the floor. If I had a torch place right on the floor level against the wall, it'd break the sand block upon contact.
Now, if we add the same principals but raise the torch one block, the sand will fall below the torch and land on the floor, then other blocks above will break as it follows the principals in the last example.
Here's the gif version of what I'm explaining: https://gyazo.com/a4892636351d056765f539b4a71bf05f
Thank you, <3
That's intended, because falling sand is an entity which falls through non solid blocks. when the sand entity stops falling it checks exactly where it is to see if it can place a block of sand. if it's air, water or lava it will place. Otherwise it will just drop the item. You can see this happening if you drop sand on a trapdoor or a slab