Can't generate "Social" type caption in some languages

When using the Image Caption Generator, I can generate “ALT text” and “Accurate” captions in any language. But at least some languages get the response “Sorry, I can’t help you with that” if I pick “Social” as the caption type.

I didn’t test them all but here’s a sample that I did test:

Languages that work with “Social” type:
English (US)
English (UK)
English (Canada)
English (Australia)
Kurdish
Esperanto
Basque
Afrikaans
Scots Gaelic

Languages that don’t work:
French
German
Greek
Hungarian
Irish
Uzbek