Crash after accessing QQuickWebEngineProfile::defaultProfile on some machines

On some machines using the QQuickWebEngineProfile::defaultProfile seems to lead to a crash.

• The problem has occurred with multiple Qt versions on multiple machines since the release of Qt 5.6 with a fairly similar call stack each time.
• Updates to chromium version seem to increase the frequency of crashes
• Reinstalling the application also seems to fix the problem as well.
• Seems like it could be related to overprotective firewall / anti virus

Steps to reproduce the crash:

In the attached example project there's a small sample code that demonstrates what is done in the application before the crash. Since the crash seems to be heavily dependent on the run environment it's difficult to say with 100% certainty whether this example is enough to reproduce the crash.

Callstack from a crash in the attached .txt file.