Skin selection in champion select

Hello dear Riot,

i was wondering what may cause this weird behaviour in champion select. I play mostly ARAM and every time I get a champion I had before it switches the skin randomly. Usually how i can remember it: You pick a skin and it will be preselected for any future time you play the champion again. And now it seems to be another randomly chosen skin.

It's not gamechanging, I know. But it is frustrating if you go to the toilet after you picked or similar and you find yourself playing with a random or sometimes bad looking skin instead of that awesome one you payed tons of money for.

Thanks for looking into it.