[Gameplay] Hydra active doesn't apply spell effects

The ACTIVE of Ravenous Hydra / Tiamat does not apply the slow from Rylai's, nor the burn passive from Liandry's. Based on trying it out in a custom game, I believe that it also doesn't apply spell vamp, but it's very difficult to tell.

To reproduce the issue, purchase a Tiamat/Hydra and a Liandry's/Rylai's. Use the Tiamat/Hydra active on any target, it won't apply the slow/burn. This happens with 100% frequency (best I can tell).

I don't know if this is the intended interaction between these items or not, but every other item that directly damages with an active (at least on SR, it occurs to me right now that I haven't tried Blackfire Torch) applies Rylai's slow, Liandry's burn, and spell vamp with their actives. The passive of Hydra/Tiamat not applying these spell effects is what I would expect, but not the actives.

And yes, I know it's a weird combination of items, but I frequently play AD/Hybrid Katarina with a hydra + haunting guise, so I'd appreciate that correction if it's unintended, or, if intended, an explanation of why my expectations are wrong.

Thanks, and happy holidays!