For me personally, cobblestone stairs seem to be the only blocks affected. Whenever cobblestone stairs are put down in any of my worlds, the stairs will disappear from wherever they were placed after quitting the session. Once I open the world again the stairs I place disappear. This has started to occur on August 24th, and any cobblestone stairs I placed before then still remains, however if I were to break these stairs on my world that were placed previously, I cannot replace them since the new stairs will disappear. Again, this affects all of my worlds (even new one I create). I do not know if any other type of block is affected the same way.