I want to look into this further, as I was unable to replicate your issue. Could you please let me know what are the steps you took when you logged-in to your account? Have you tried logging in to an unknown device, or a device that you will be logging in for the first time, to see if you will be asked to complete the 2-step verification?
A few days ago I got a message from Upwork suggesting me take the 2 step verification. I did it, but the message is still there. I want to know if there's something I'm missing.