Created a world in the lastest release, went right and find a sand wall, it wont stop spawning sand, it extend to the end of the world 
I tried creating a new world in this build and went all the way to the right and the upper right but I’m not seeing it… Can you see if there’s a particular type of pixel that is spawning the sand?
Also does this always happen if you create a new world? Does it happen at the left edge of the world too?