Even though for 1 day Sona's E was buffed to 30% at rank 1, her winrate didn't even change

Judging by the 19th when the patch went live it appears that it had no effect to her winrate

This is not the first time this has happened, I'd say around 75% of her lifetime changes have done absolutely nothing to her winrate, be it buffs or nerfs she is always going to hover around 50-54% winrate (and that drop is essentially due to her never being meta for around 3 years now) I'd say this is why Riot have such trouble balancing her, most things they throw at her (as long as not being drastic) will show no clear statistics into how it effected her