I asked WPML support but they don’t understand why the issue:
On my website (link on private) on a mobil phone the menu display well the flag in my main language (french)
But on English the flag do not show.
I set yet to display it on both on WPML settings.
Any idea?
Did you sync or translate the main menu? If you haven’t done so, please check the following documentation for more information about menu translations.