Unable to input Chinese in MainWindow's submenu using Qt Designer

To reproduce:

1. Create a new Qt Widget project with MainWindow base class.
2. Use Qt Designer to open mainwindow.ui
3. Input something in the menu bar (Chinese IM available here)
4. Try to input Chinese using Windows' Chinese IM, finding that it cannot switch to Chinese

Note that this is the same issue with [QTBUG-65840] 在qt 设计师软件的图形用户界面下：编辑二级菜单名字，不能输入中文；google translated: In the qt designer software graphical user interface: Edit the second menu name, can not enter Chinese - Qt Bug Tracker