Connection Lost - Minecart with Command Block

While testing the 13w39b-snapshot I tried the new minecarts with commandblock. I've set up the constraption seen in screenshot two with the commandblock set up to spawn falling sand 10 blocks above itself.

I almost immediatly got kicked and the client showed the error message seen in screenshot one. When trying to reconnect I instantly get kicked after loading the first chunks.

When done in the right moment (about 50-100ms timespan) I'm able to teleport via the server console and play normally everywhere else on the server. It's just that spot..

Here is what the server says:

[01:42:15] [Server thread/INFO]: ignitedPotato[/109.193.xxx.xxx:37100] logged in with entity id 173 at (3898.5, 67.00999999046324, -1767.5)
[01:42:15] [Server thread/INFO]: ignitedPotato joined the game
[01:42:16] [Server thread/INFO]: ignitedPotato lost connection: TranslatableComponent{key='disconnect.genericReason', args=[Internal Exception: java.io.IOException: Die Verbindung wurde vom Kommunikationspartner zurückgesetzt], siblings=[], style=Style{hasParent=false, color=null, bold=null, italic=null, underlined=null, obfuscated=null, clickEvent=null, hoverEvent=null}}
[01:42:16] [Server thread/INFO]: ignitedPotato left the game
[01:42:16] [Netty IO #2/ERROR]: Channel became inactive!