“Use a subdirectory for the default language” does not work poperly

Hi!

When I use English as the default language on site and I activate “Use a subdirectory for the default language”, it works well in the sense that even the links without the /en/ prefix get redirected to a version with the /en/ prefix, without me having to add the /en/ manually. For example, https://mysite.com/about redirects to https://mysite.com/en/about. But when I use French as the default language, activating “Use a subdirectory for the default language, ” a link to a page like https://mysite.com/a-propos inside a button would give a 404 error, instead of redirecting to https://mysite.com/fr/a-propos. Because of that, I had to deactivate the “Use a subdirectory for the default language” option on the site where the default language is French, even though I wanted to use this feature. How can I fix that?

By the way, when “Use a subdirectory for the default language” is activated the default URL does have the /fr/ on the homepage, the navigations, and other pages. The issue is with links added manually inside of content on pages and posts. If I manually add an internal link the subdirectory for default language does not automatically populate when the default language is French. Probably the same for other languages, but I am using French as the default language.

Thanks in advance.