When teleporting area effect clouds and falling blocks with commands, their position does not visually update until after the player rejoins the world. 

Replicate it:

/summon falling_block ~ ~1 ~ {Time:-32767, NoGravity:1b, Tags:["target"]}

Move away from the area a couple of blocks

/tp @e[tag=target] ~ ~ ~

The falling block (including its hitbox with f3 + b) should still appear in the original spot. If you relog, it'll visually update. The same thing happens with area effect clouds, though I've only tested it without particles (particle: block air), and the hitbox stays put until the player relogs.