When but not solid block (for example: hopper) "in" snow layer snow stays but when you testroy block snow dissapear, and when you put that block again snow appears.
Attachments
Comments 2
This appears to be an Optifine feature - please test in an unmodified (without Optifine) game in the latest version of snapshot and see if it still occurs. If so, please force a crash by pressing F3 + C for 10 seconds while in-game and attach the crash report ([minecraft/crash-reports/crash-<DATE>-client.txt|http://hopper.minecraft.net/help/guides/finding-minecraft-data-folder]) here.
Modded clients are not supported.