Killing stray with a bow/crossbow from 50 meters doesn't give you the challenge advancement "sniper duel"

The advancement challenge "sniper duel" requires to be about 50 blocks away from the skeleton and kill it with a bow/crossbow as normally.
However, the other skeleton type, stray, doesn't give you the advancement challenge.
Here's a video of me shooting both stray and skeleton at the same position by the signs.