Mac 10.11 update makes menu bar and other stuff flicker on second monitor

Once I updated to 10.11, everytime I start a game the secondary monitor menu bar begins to flicker like mad (it's a lot faster than the video since it's capturing less FPS). It's not only the menu bar that goes funky, sometimes random elements inside windows begin to flicker as well on secondary monitor. The flicker I can try to ignore but it's extremely annoying because you lose control of your champ as well at random times, like a mini DC which can really fuck the game up for you and teammates. I submitted a support ticket as well but thought I'd create a thread too.

pls fix