I did fix the issue my self and just now have time to address it here.
The way I was able to fix it:
On my macbook I deleted the app from applications folder and then searched (via mac os search bar) and deleted any mentions of upwork on the computer. After reinstalling the application I was able to log in and start loggin hours.
I had a same problem on Ubuntu 18.04.
In addition to unstalling the previous version and installing new one, I needed to delete application cache:
Click on system tray Upwork icon, then Settings, then Advanced, then "Clear Cache And Restart".