Apple - "Start Screensaver" hotcorner no longer works under El Capitan beta

What worked for me:

1) Change the hot corner action to something different. It should work.

2) Restart your Mac

3) Change the hot corner back to the original action.

I just checked that the action keeps working after a restart.

I'm on MBP 15'' Retina Mid-2014 with El Capitan.

Go to System Preferences, change your hot corners to other random ones, restart your Mac, and then go back to settings and change hot corners back to starting screensaver.