Prophetic Twilight Stone Doesn't seem to work

So I wanted to experiment during raid as a healer and was thinking of pairing a healing stone(Deluging Water Stone) with a damage stone(Humming Arcane Stone) with Prophetic Twilight Stone.

I was thinking I could maybe get a little damage increase while healing.

Looking at my logs this just straight up doesn’t work. I see MANY procs of the deluging water stone with zero Humming arcane stone.

What’s going on? Was I just wrong to think that it would proc off the healing procs? Or is it something else?