If you place a trapdoor facing West or East (Doesn't matter if the trapdoor is placed on the half bottom part of the block or in the half top part), and then you power it (If it is an iron trapdoor, you need a redstone signal, and if it is a wooden trapdoor you can just right click to "open" it) the texture will be in the wrong postition but the hitbox will be in the right and it has no texture.
In the screenshots you can see the bug in this order (Or look at the "F3" mode block info):
1. Facing East, Half Top.
2. Facing East, Half Bottom.
3. Facing West, Half Bottom.
4. Facing West, Half Top.
(PD: Sorry if i spelled something wrong).