Storefront child theme translation

Hi guys,

Odd things happens with translation. I translated Storefront, tried to apply it to a child theme and some strings are not translated on front end. I followed WooThemes docs, but no result. Put sr_RS.po and .mo files in child theme language folder, with no suffix, just country code in name and some strings are still English. To be more precise, in primary menu, top right, cart says “items” although it is translated. Even more odd, when I empty cache, for a moment there is translated string, and when cache emptying is finished it remains the same “items”. WP is up to date, so is WooCommerce and Storefront. WP is localized Serbian version. Any thoughts?

Cheers,
Aleksa