UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/67.0.3396.99 Safari/537.36

Steps to reproduce the problem:
Unfortunately, ave been unsuccessful creating a standalone reproduction of this behavior outside of internal app.

What is the expected behavior?

What went wrong?
In an internal application, since Chrome 66, certain content has become un-scrollable via *mousewheel* only. Chrome is the only browser this behavior is observed. Earlier versions of Chromium/Chrome do not exhibit this behavior. Checked Chrome Canary 69 to see if it was resolved in a future release, and the behavior still exists.

Did this work before? Yes 65

Chrome version: 67.0.3396.99  Channel: stable
OS Version: OS X 10.12.6
Flash Version: 

During troubleshooting I disabled the Threaded Scrolling flag in Chrome, and the issue was fixed and content was scrollable. Obviously this isn't a workable solution, but this seems like something was introduced in Chrome 66 that changed the way mousewheel scrolling works fundamentally. Again, this is only observed with mousewheel. Keyboard scrolling worked just fine.

I eventually found a very odd workaround that made the content scrollable, but doesn't make much sense:

- If the scrollable content had an explicit background-color set that was *not* transparent, the content became scrollable. If however, the content had a transparent background-color or inherited a background-color, the content became unscrollable via mousewheel.