Can be found in either survival or creative game mode. When a trapdoor is placed over a hole/tunnel into the ground it will function as it should. Although when you open it and attempt to go down, your character will sometimes get hung up on the small portion of the trapdoor. To go down into the tunnel you have to move around until you can fit through the opening. Also if you walk on a trapdoor when it is closed you will bounce/jump for no reason
1. Create a whole in the ground that is at least more than 5 blocks deep
2. Place a trap door at the top of the hole and close it
3. Open the trapdoor and try to go down the hole
4. If you are unable to fall down the hole, try pivoting and turning until you can do so
5. Also try having stairs down the hole and attempt going up and out with the trapdoor open. You may get hung up again. Then try falling again to see that you still get hung up.