Having trouble with four-letter cultures

So far I’ve been successful setting languages like en, es, ru… However I’m trying with chinese (both Traditional and Simplified) and I can’t make it work. I’m testing every combination, zh-Hans, zh_Hant, zh-HANS… None of them works. Any ideas?

Yes, I’ve set both translations in the localization dashboards and set everything just like the oher languages. In fact, it works if I just use the basic ‘zh’. Though I need to work with both hans and hant.