For that I need to type English, French and Chinese, I'm using fcitx to manage the Chinese input methods and I need to change the keyboard layout very often. I've checked the option "Show the input source in the top menu bar", but it doesn't works.
But I find out that, when I login as a guest, all the input things works perfectly, but when I login as my current user, the keyboard layout icon is not displayed. Just as the image showed below:
So I guess it might be a user configuration error, did you know where to configure the Panel icons or reinitialize user's configure?