Falling Sand created by /summon is invisible

When I summon Falling Sand using "/summon FallingSand ~ ~ ~

{Time:1}

" the Falling Sand is invisible. As soon as it lands it becomes a solid block which is visible.
Falling Sand created naturaly (by letting Sand fall...) is visible.
I couldn't find anything special about the summond Falling Sand when looking at it using an NBT explorer.
The Falling Sand is still invisible after relogging.
In 1.7.4 everything is working fine.