When playing Minecraft 1.7.2 and the snapshots last two snapshots before release if during single player or multilayer i hold any type of torch redstone or regular or a sapling of any type then terrain unloads leaving only water lava mobs, passive and aggressive as well as torches visible. Blocks are still present as the hit-boxes can be highlighted and be walked into however are invisible. After this has happened if i continue to hold the torch or sapling then those things that remain flash on and off going from invisible to visible but blocks do not reappear. The only way i have found to resolve this which still does not prevent the issue from happening is to drop the item use f3 and a to reload the terrain then exit Minecraft load up the world again press f3 and a again and then the blocks reappear . Attached is a screenshot of the issue. Hope to see it fixed ass it makes playing survival a bit difficult when you cant place a torch.