Problem updating translation files

[zyON]

I'm migrating a site to PW using Multi-Language support (5 languages) and all is really working very well except for one annoying thing: 

I'm translating strings using the translation files (json) but when I try to update a file already linked on the Setup > Languages > language section, I can see the new strings  I've added to the document with the corresponding textfields but when I save the changes, the field (or fields) do not hold the new value. 

I get the messages: 

•  1 translations changed

•  Saved site--templates--property-php

But the field is blank and there's no change to the .json file. 

Anyone experienced this issue?