When pulling out a block from under a gravity affected block such as sand, the block will break instead of falling. (The second image depicts the block breaking, the log is still there, just doing that weird flash)
When pulling out a block from under a gravity affected block such as sand, the block will break instead of falling. (The second image depicts the block breaking, the log is still there, just doing that weird flash)
Confirmed on 1.2.2.3 Windows 10. The first block breaks when the piston retracts. If there are additional gravity affected blocks on top of that, they fall as expected.