UserAgent: Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/67.0.3396.62 Safari/537.36

Steps to reproduce the problem:
1. Open 'Network' tab in DevTools
2. Select an XHR request from sidebar (in my case, a request that has returned an error needing debugging)
3. Click 'Preview'

What is the expected behavior?
Long content in preview window should be scrollable.  

What went wrong?
Scrollbars are present but cannot be scrolled by mousewheel, clicking the 'down arrow' or by keyboard controls. 

Did this work before? Yes Version previous to latest update (Chrome 67)

Chrome version: 67.0.3396.62  Channel: stable
OS Version: 6.1 (Windows 7, Windows Server 2008 R2)
Flash Version: Shockwave Flash 29.0 r0