Sorry, your original post said nothing of the sort. I missed the one sentence in your second post where you did say that as my eyes jumped right to the video. Your first post just said the skill bugged/failed... It didn't fail. You just didn't see the effect. Not really the same thing. You switched away from the combat log, but the bits of the video I watched which had the combat log showed:
* the skill triggered
* the damage effect triggered
* the burning effect triggered
* the weakness triggered
* no projectiles were evidently reflected, but neither did any hit you, that I saw at least
That seems to suggest that there were no projectiles to reflect, and other than the visual bug ollbertan mentioned, the skill is working... not failing. The only thing you're not getting is visual feedback that everything is working as intended. That's annoying, but doesn't seem to make the skill "unusable." Your original post--while didn't say so outright--strongly suggested the skill often wasn't working at all ("33% of the time it doesn't spawn at all (but still consumes ammo)"), but that's not the case.