Linux Mint 19 and Yubikey

I recently upgraded Linux Mint from version 18 (18.3) to 19 (19.1). After the upgrade, my Yubikey USB device stopped working in Chrome. I was getting an "Unexpected error" message in a red box in the 2FA widget in our organization's federated login page.

Originally, I thought this may have been a Chrome configuration issue, but it turned out to be an OS configuration issue. I followed the steps on the Yubico site to get the U2F Yubikey working on Linux. I didn't have to do Step 1. Step 2 was the critical step.

Once I rebooted, my Yubikey started working again.