UserAgent: Mozilla/5.0 (X11; CrOS x86_64 11151.29.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/71.0.3578.49 Safari/537.36
Platform: 11151.29.0 (Official Build) beta-channel eve

Steps to reproduce the problem:
1. Plug in a YubiKey (4C Nano in this case)
2. Flip Pixelbook/Chromebook into tablet mode
3. Tap on a text field

What is the expected behavior?
The virtual keyboard appears so that text may be entered.

What went wrong?
The virtual keyboard does not appear.

Did this work before? N/A 

Chrome version: 71.0.3578.49  Channel: beta
OS Version: 11151.29.0
Flash Version: 

I tried unplugging the YubiKey and repeating the steps above: the keyboard appears!

I guess that the YubiKey is detected as an external keyboard and so the normal virtual keyboard behavior is disabled.