I had this happen briefly before, but now it's back. When I mine a block, it disappears, then reappears. Then, 1 to 10 seconds later, the block disappears again and the item is dropped. The game was working fine all day, but it started happening about an hour ago. When I restarted my computer, it made the delay even worse. Happens with all tools, but only occurs when mining blocks. Ladders, torches, etc. work fine.
Version 1.8 vanilla. No mods, no textures, etc. Windows 7 Home Premium x64, 8GB RAM, Java 1.7.67 x64 (happens with x86 too), Quad Core Intel i5-3210M. Intel HD Graphics 4000.
Update: It seems I left my dispenser turned on at my chicken farm. So 4 gold swords, 2 iron swords, and 15 stacks of feathers later, I am no longer having an issue.
Confirmed it occurs in 1.8. I just built a rail to the wrong spot >.>