Solution - Second Monitor Not Working
 

I have been tearing my hair out trying to figure out why I couldn't get a second monitor to work (after the recent Mac OS update). I finally found a solution that worked for me:

a) Connect the first external display to HDMI display 2
b) Connect the second external display to DisplayPort Display 3

Connecting one monitor to Display 1 does not work. Connecting both monitors to HDMI (1 and 2 or 2 and 3) does not work.

Go figure... Note: both are treated as "virtual displays" now.

Hope this helps...

Hello rcusick,

Thank you so much for sharing your solution.
We really appreciate you taking the time to detail what worked for you.