Whenever you break a block (any block you can place down) it very often POP back. How many times it pops back varies from time to time! Sometimes 10, sometimes only 1. But its really annoying whenever your gonna remove big buildings or many blocks. I wondered why its like this, and if it will get fixed any time soon?
If you are building or destroying over the void with no block beneath it lags very often, may ir may not play a factor in what you are experiencing.