Summoning falling sand with a tile ID "minecraft:<block>" spawns normal falling sand (with sand ID).

Command used :

/summon FallingSand ~ ~2 ~2 {TileID:minecraft:stone,Time:1}

(spawns normal falling sand, not stone, and it is the same for other blocks)

PS : Using the IDs of the blocks in the command works.

/summon FallingSand ~ ~2 ~2 {TileID:1,Time:1}

spawns falling sand with the ID of stone and works as it should.
And replacing TileID by Block works also.

/summon FallingSand ~ ~2 ~2 {Block:minecraft:stone,Time:1}

spawns falling sand with the ID of stone also.