4K Issues (workaround, but not really)
I've been playing league in 4K for about a year now and after every patch I hope Riot would provide real support for 4K users, but to no avail. I have been messing around with a couple of things to get the text scaling right and I thought I would share my experiences with you and Riot to see if it helps.
After any new patch (5.19 being the most recent) the loading screen does not scale right. Here is an image of what I see on screen. https://dl.dropboxusercontent.com/u/16932736/LoL%204K%20Issues%20images/game%20correct%20scaling%20loading%20screen.jpg
When the game loads as you can see I am missing about 3/4 of my screen. https://dl.dropboxusercontent.com/u/16932736/LoL%204K%20Issues%20images/game%20correct%20scaling%20in%20game%20screen%20missing.jpg
The only way to solve this is to change the video option from Borderless to Full screen and then back to borderless (I always play borderless). If I leave it at full screen I can not see my cursor!
I have to do this after every patch and when I do the text scaling is perfect for that game, as shown here. https://dl.dropboxusercontent.com/u/16932736/LoL%204K%20Issues%20images/game%20correct%20scaling%20in%20game%20video%20settings%20change.jpg
The issue is the next time I load a game the text scaling is all wrong, as shown here. https://dl.dropboxusercontent.com/u/16932736/LoL%204K%20Issues%20images/game%20incorrect%20scaling%20when%20props%20changed.jpg
I did find a way to solve this but the only problem is that I have to go through the whole shenanigans of changing the from borderless/full screen again. What seems to happen is "Disable display scaling on high DPI settings" is ticked when I select properties on the LOL Client program. Shown here... https://dl.dropboxusercontent.com/u/16932736/LoL%204K%20Issues%20images/props%20after%20game.JPG
If I remove the tick, I have to start this whole process again, but the correct scaling only last for that one game. So If I wanted the correct scaling every time I would have to untick disable scaling before I started a new game and then once in the game change the video options. Which is rubbish, especially if you want to invade, as it takes me about 3 mins just to sort the resolution out. You try moving an invisible cursor around :)
Anyway, this may help some of you and it may help Riot on fixing it for good.
Just thought I would share my experience.