Chrome blocks plug-in

Hello.

What WordPress Address (URL) and Site Address (URL) do you have in the Settings->General?

You must have the protocol https

Thanks for the quick response.

WordPress Address: https://www.cent-cinq.fr
Site Address: https://www.cent-cinq.fr

Why https? And how do I get the “s”?

if you go to URL https://www.cent-cinq.fr/en/ the button work correctly
when you go to URL https://www.cent-cinq.fr/en/ the button don’t show, because ‘Mixed Content’

OK. What does “Mixed Content” mean – and what do I do about it?
Thanks for your help so far.

Your site is accessible at two addresses https://www.cent-cinq.fr/en/ & https://www.cent-cinq.fr/en/

Must be only one URL http or https.
If you change WordPress Address and Site Address on https://www.cent-cinq.fr/en/, the issue will fix

Job done!
Thanks for your help. It seems I learn a little every day.