Why doesn't Sivir's Ricochet proc spell effects?

I tried playing Sivir recently thinking I could use Comet and Manaflow Band via Ricochets but some odd minutes in the game I noticed that none of the were being proced despite her richochets hitting her opponents. Its extremely odd since the wording on Comet and Manaflow states it procs whenever you damage a champion with an ability. Since her W is considered a damaging ability I thought it would be a decent harass tool. However that doesnt seem to be the case. So then I try Aery due to me thinking of it being more broader but again, thats not the case.

What about Ravenous Hunter? Nope. Even though it procs from Sunfire Cape and Torment, for some reason Sivir's W doesnt. The only other champion that suffers from this would be Rammus and his defensive curl even though Thornmail allows it despite functioning the same.

Is this a bug or was this truly intended? If it was intended then all of my whys? Because you would think they would perfectly sync together.