UserAgent: Mozilla/5.0 (X11; CrOS x86_64 10718.71.2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/68.0.3440.87 Safari/537.36
Platform: 10718.71.2 (Official Build) beta-channel caroline

Steps to reproduce the problem:
1. Connect Chromebook to external monitor using USB-C cable running at 3840x1600 resolution.
2. Monitor flickers often - sometimes going completely black
3. Changing resolution to 2560x1080 eliminates the problem

What is the expected behavior?
The Chromebook handles the external display at the higher resolution without flickering

What went wrong?
Chrome OS simply doesn't appear able to handle the higher resolution on an external monitor.

Did this work before? N/A 

Chrome version: 68.0.3440.87  Channel: beta
OS Version: 10718.71.2
Flash Version: Shockwave Flash 30.0 r0

There are other open bugs listed that are somewhat similar to this (related to display issues) - but nothing with recent activity.