This is a weird glitch you can say, as many Mojang workers have tried there hardest to fix this issue it still occurred but in a different fashion. I was testing different blocks to see what would happen against a Piston/StickyPiston Glass did disappear but I was not able to catch that on camera, I did however catch LeafBlocks Disappearing and how it can effect the pvp side of things. Follow the links I show to see how it works and how it effects PvP/Traps.

https://www.youtube.com/watch?v=kYH4iAL4UfQ

https://www.youtube.com/watch?v=BoKrV2cHYMI