Starting with the second snapshot released for minecraft 1.8, blocks placed in an rectangle, about 8 blocks wide and 1 long, straight up, and then 16 blocks up, it becomes 2 long, will be erased after getting out of the game and back in.

The snapshot 14w04a and b resulted in something different. I had placed some stone blocks, and was replacing them with cobblestone. Only had one layer of stone, then I destroyed it then built a stone wall. After getting back out of the game and back in, all the cobblestone that was placed was erased and the stone was back.

After 14w05a, the stone stayed gone after i destroyed it, but now everything i put in that spot disappears as well. This is the only place that I know of on the map where this happens.

If needed, can film myself placing the blocks down, getting out of the game and back in and having them disappear.

Thank you for your time in this matter.