I've had this problem for a while but I found a "fix" pretty quick and it only mildy annoyes me.
My default input is the Korean Microsoft IME keyboard which I dont have any problem with in other programms, hell even in the LoL client it works as it should.
The problem starts as soon as I'm ingame.
Even if I was using Roman letters, LoL switches to Korean. Not only that, they aren't even displayed properly and all I get is empty boxes similar to this □.
Usally I notice pretty quick and mildy annoyed delete the "korean" right away and switch back. But often enough the next time I open chat again or I want to type something in the shop it has switched to "korean" again.
My "fix" was to just use the UK keyboard as input when playing League but even I sometimes forget and those 4 seconds can be crucial sometimes.
I remember a while back I didn't have that bug but it's returned it its full glory.
Anybody know proper fix? Should I just reinstall LoL? (I think it has been the cause of other issues too)
Thank you for your time~
edit: Korean keybords have both roman and korean letters which can be switched through pressing a button.