OJS Locale not working

I´m using OJS (Updated from 3.1.2)
The translation is working fine except in all my custom plugins and templates. Every plugin added don´t translate the tags.
I have been searching for a solution but I only found this one:

But my table has supportedFormLocales correctly:
For example I created a block to show ISSN:
I build it from the “developed by” block, which is translating correctly. My block is also working fine except for the translation.
I used the correct sintaxis:
I also create a .po with the sintaxis:
But the translation its not working, and i don´t know what I´m doing wrong.
I don´t know what else must i do to make custom locales work.
Thank you very very much

All my plugins didn´t appear in custom locale settings list. Must i do something to “register” that locales in some place? I can´t find any info of the step i´m missing.

Thanks again

I have made a change in the announcements block, a simple change, and now that block is not translating. So i am thinking it has something to be with codification.
I will try to configure my editor to make it work again but, does someone know how must i save the files for ojs 3?
Thank you very much to this great community.

Finally I fixed it saving files with utf-8 without BOM codification.