QWebEngineView in a QDockWidget fails to render when floating state changes while runtime

[seb_berlin]

Hello,
I use a QWebEngineView inside of a QDockWidget on a desktop application on Windows.

After starting the application everything looks as expected, doesn't matter, if the initial state of the dock widget is floating or not. When I change now the state while dragging the widget I get the following error message:

composeAndFlush: makeCurrent() failed

and the content of the QWebEngineView is not rendered. When I move the widget back, so that it gets its origin state, it renders as expected.
I hadn't this issue on 5.8, but on 5.11.

Any ideas?
Thanks,
Sebastian