Deadlock on close

On Windows (only, other platforms seem unaffected), using 5.11.1, we seem to get a deadlock on closing our QtQuick application. Previous versions of Qt are unaffected. I haven't really spent very long looking into this, but it seems to me thread #0 and #22 are the relevant ones here (see attached stack dump). Downgrading to 5.11.0 has solved this issue for now, so I guess the search space is at least relatively small.