So I just started making a house in creative when I decided that my door wasn't placed properly. And to my surprise, the door dropped. I think it was because I mined the top part of the door, mostly because I tested it myself. So, the first thing I thought was hey, why not report it to Mojang. So yeah that's why I'm making this.

To recreate it: start a world, place a door, and mine the top of it.
PS: make sure to place it on the ground. Not the side of something.