QtWebEngine shows black window on Windows Server 2008 R2

Same as QTBUG-70195, displaying a QWebEngineView on Windows Server 2008 R2 via Remote Desktop the widget is painted black.

Reproduced using simplebrowser example release and debug builds for 5.14.2 and 5.15.2, using pre-built binaries downloaded from Qt. I deployed simplebrowser using windeployqt so I think it should have all necessary components.

I have installed "Desktop Experience" to make media features available (not installed by default on Windows Server) and there was no difference.

I have tried running with -disable-gpu,-single-process and with QT_OPENGL=software and still no difference.

I have attached a debugview log of running simplebrowser with the above (with --v=1).

I have also attached the output from qtdiag.exe as requested and never provided in the related bug report.