UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/64.0.3282.186 Safari/537.36

Steps to reproduce the problem:
1. Right click on a chrome folder bookmark and select "Add Folder..."

What is the expected behavior?
The browser should display an input dialog to get the new folder's name and then should add it once the dialog has been confirmed.

What went wrong?
Instead of appearing horizontally centred, the dialog opened in the top-left corner and I got immediately logged out of my account. When I logged back in Chrome was displaying an unexpected error. Kind of scary!

Did this work before? No 

Chrome version: 64.0.3282.186  Channel: stable
OS Version: OS X 10.13.2
Flash Version: Shockwave Flash 28.0 r0

I usually work with my Macbook Pro plugged into another screen and I keep Chrome open as a fullscreen app on my device and a tab of Chrome (using a webapp) on the other screen. I know that Mac OSX something behaves weirdly with fullscreen apps, so that may be part of the solution.