Multiple languages not showing in dropdown

I have two websites – A and B with overlapping content.

I would like the language selector dropdown on website A to link to a specific page on website B.

For example, I would like a user of website A to be able to click on the French flag and be taken to a French page on website B.

In settings –> url modification I have selected ‘The language is set from different domains’ and entered the specific links to website B for each language

However in the navigation of website A only English shows – no other languages drop down.

Thanks for your help

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