hr.po lang file in child theme does not work

I created hr.po (Croatian) lang file in Virtue base theme and translated few strings – 404 page just for test. It works, returns Croatian translation as it should.
But, when I put same files (po, mo) inside child theme in “language” folder (same path as in base theme), it does not work. Other files override base theme as it should be. I wanted to put translation there in case Virtue theme us updated, so hr.po is not overwritten or something like that.

Help is appreciated, I would really like to understand why it does not work.