Polylang – String translations not being picked up

Ok, I’m working on a new site that I want to be bilingual English-Spanish with English as default.

The main menu translations and language switch work fine, but for some reason the string text translations are not working.

I downloaded the .po file from the languages directory of my theme (WP Prosperity), added the translations in Poedit, and saved the new file along with a compiled .mo one. These two are named like the original .po file, with es_ES added at the end.

So, I uploaded the two new files to the same directory (while keeping the original file) and…. nothing happens.

If I go to the “Strings translation” tab in Settings > Languages, nothing has changed (shouldn’t I see all those I added in the new files?), and a quick test shows that strings like “read more” are still shown in English even in a post created in Spanish.

Any ideas about what I’m doing wrong?