Since the today patch update, LOL cannot be used on iMac to play at native 1440p

Today ,my League of Legends updated, but i cannot longer use the normal resolution for my 5k iMac-> 1440p it shows half of the screen please fix since this is a common big issue, tried already on 3x imacs (2x 5kiMac late 2014 ) and 1x late 2013 27" imac