Black Screened after game launches?

Hey! Since patch 5.13, I've had multiple games where after champion select the game launches into a black screen. I tried restarting the client, restarting my computer, restarting the router, but none fix this issue. It does not happen every game I play, but happened twice tonight, causing me to get a low priority queue. I was wondering if anybody else was having this issue, and if someone could possibly help me with a fix. This has never happened to me before. The problem happened only after the new patch. Thanks~!