[Client] Runes are bugged, and have been bugged, for weeks.
Runes have been completely bugged on the updated client for a large number of people, including myself, for several weeks now. You have removed the only workaround that had any consistency, in using the legacy client, despite being aware of this due to the number of people reporting it. You have not said anything about the problem — even just letting us know you're working on it. No information on how to avoid it. As far as I can tell, everybody experiencing it just started having it happen to them at some point after 7.7.
This is a pretty critical glitch. Runes are incredibly important to the game, and unless you've been playing the game several hours a day every day for a long damn time, or only ever spent IP on runes and bought everything else with RP, it's unlikely you have every rune page fully stocked. You're going to need to change them from time to time as the game itself changes. You're going to want to adjust them for trying out specific champions and specific playstyles. Right now, a lot of people can't, and we haven't even been told if a fix is in development yet.
I am hoping 7.9's bug fix section has some light to shed on this — at the least acknowledging the problem's existence. If it doesn't, I am going to be very disappointed.