If you place a trapdoor then flick it down, or up. When you quit to title screen, and then go back into the game, the trapdoors are back to their original position. This is on single-player survival world, created when 0.13.0 Beta 1, now in Beta 4. This bug is continuing, it has only happened since I join the testing group and downloaded the Beta versions.

If [o] means open(original position) and [c] closed, position user wants it at below is a mini diagram of what happens

place the trapdoor [o]
flick trapdoor to place wanted [c]
QUIT TO TITLE
JOIN WORLD
trapdoor is in [o]