And to add a new variable, based on BetterRed's detective work on markdown support, i was able to search qtbugs better and as it turns out WebEngine did make some windows specific changes related to their clipboard code:
https://codereview.qt-project.org/c/...ipboard_qt.cpp
from this issue:
https://bugreports.qt.io/browse/QTBUG-100806
which indicates that Window's requires both the html and body tags on html content so that pasting html actually works on Windows.
The latest fragments from calibre do not include those pieces.