In case anyone else has my issue....
My monitors stopped working on my macbook air when I upgraded to Catalina. I followed the instructions here:
https://support.displaylink.com/know...r-only-one-mon
One last step that needed to be done after the above instructions was to go to Security and Privacy in System Preferences. In the General tab at the bottom is a new message I hadn't seen before that read "Some system software was blocked from loading" with an "Allow" button. I clicked that button and saw DisplayLink in the list. I checked the box for it and restarted and my monitors work now.