Can't input emoji on macOS 10.12.5

On latest macOS, when you enter text in a QLineEdit or other text editing widgets such as QPlainTextEdit, press Ctrl+Cmd+Space to bring up system emoji input popup window, click on an emoji, it will not be entered into the text input area. Same code works fine on Qt 5.7.1. This is show-stopper for me as I have to switch back to using 5.7.1 again

For some reason I can't upload my test code. But it is very easy to make one. Just create a minimal QMainWindow project, add a QLineEdit on to the main window. Add a "Edit"->"Copy" menu item on the menu bar. (This step is needed to make QLineEdit respond to system emoji hot-key Ctrl+Cmd+Space bar). That's it. When run it, try enter some text and then press Ctrl+Cmd+Space to try emoji input. You will see the issue.