White screen after matches

Every single time I'm done with a match, the client keeps showing me this. I can hear the audio of like, chests opening or whatever happens on the post-game screen, but the thing looks like this and doesn't respond to clicking anywhere. I'm running a high end gaming pc so it probably isn't a graphics or performance issue, and I've played league in the past without it doing this, which leads me to believe it's a recent thing. (I haven't played in like a year or more, so I can't narrow down the timeframe.) Any suggestions/ideas?