I'm using QWebEngineView in a similar way as tooltip for application.
After i perform QWebEngineView::hide() and QWebEngineView::show() it stops responding to QWebEngineView::setHtml().
That doesn't happens always but it is definitely related to a QWebEngineView::hide() and will happena fter couple of hide() calls. If I hide it any other way, for example resize(0, 0) issue doesn't happen.