I think this has been a bug since the observer was added in 0.15. If you look at an observer in inventory item form or as an item entity, you'll notice that the arrow texture on the top of the observer is pointing the wrong direction. (Compare to observer as a block placed in the world, and to Java Edition.)

Note that this bug might even affect other block items, too. It's hard to tell, though, since most top textures don't have any obvious directionality.

Steps to Reproduce:

1. Place an observer block.
2. Throw an observer item on the ground, or simply look at the one in your inventory.
3. Notice how the arrow texture is pointing towards the observing side, rather than the output side. Compare to the block placed in the world and to Java Edition.