Problem with the current language

Hi,

I have got a problem with current languages. There is 3 languages (en/fr/vi) on my blog.
On my blog, i installed wordpress 4.3, polylang 1.7.2 and already deactived other plugins. EN is default language.
But when i get pll_current_language() in fr/vi is always return to “en”.
I event tested it with wordpress theme.

I found a article near the same my problem : http://wordpress.stackexchange.com/questions/140387/get-locale-behaving-strange-in-same-functions-php-file
the language_attributes() always return to “en-US”.

Anybody got the same problem? Could you help me fix it?

Thanks

https://ww.wp.xz.cn/plugins/polylang/