Dont work

there are 2 (or more) sites – the switch on default will work correctly, but on the child ones you cannot select (and add to the menu switch) the main language.

https://drive.google.com/file/d/1S4UReMdnOJzdWmSojsPLYnR-h0mC1fn_/view?usp=sharing

The page I need help with: [log in to see the link]