[סגור] Only the current page language available in language switcher of pages like קישור נסתר...

Background of the issue:
In my website, there are a couple of post archive pages, for example - קישור נסתר. This is an archive page for school post type with school-type taxonomy term - primary-schools and in this page, I can see both languages (French and English) are available in the language switcher. In my website, there is another type of archive page, just adding another taxonomy's term at the end of the URL like this קישור נסתר, but in this page, I can only see the current language in the language switcher.

Symptoms:
In the URL קישור נסתר, I can only see the current language in the language switcher. For example, if I visit קישור נסתר I can only see English in the language switcher, because this is an English page, and vice versa. But there should be both French and English buttons available.

Questions:
Why is the language switcher only showing the current language on the URL קישור נסתר?
How can I make both French and English buttons available in the language switcher for the URL קישור נסתר?