@KH-219Design glad to know I helped and thanks again for your input!
After working perfectly during one full day of tests, the problem resurfaced again yesterday. Anything built in C++ using QWebEngineView works for all of my tests until it gets to one of the problem URLs, then abruptly crashes. No other URLs cause this problem and the page in question loads fine in any "real" browser I try it in.
Since I'm not tied to any particular version of Qt, I've downgraded from Qt 5.14.2 to Qt 5.13.2.
The Qt 5.13.2 QWebEngineView is not crashing. Also, it seems faster than Qt 5.14.2, and doesn't have another annoying behaviour which I believe to be graphics driver-related, which is that for certain pages of a well known UK based left wing newspaper the URL loads and then the whole web engine widget goes grey, and the program freezes.
With no interest in faffing around further, I'm concluding that inside Qt 5.14.2, either the implementation of Chromium or the Qt WebEngine wrapper is buggy, at least for my particular combination of hardware and software.
Original Problem
Using MSVC 2017 + Qt 5.14.2, QWebEngineView crashes randomly on certain URLs which do not appear to be doing anything out of the ordinary.
Solution
Avoid Qt 5.14.2, or at least avoid the pre-built MSVC 2017 version which comes when you use the offline installer for Qt 5.14.2. In my case this meant downgrading to Qt 5.13.2.