Strings translated with _e showing untranslated

Hi there. I’m using Loco Translate and also “Envira Gallery Lite” plugin. I’ve seen that many strings at Envira admin section are shown in English, despite seeing them translated to spanish from the Loco panel, and in the .mo/.po files.
Quickly checking the plugin’s code I see those strings are shown using _e function.
Where could be the problem?
Thanks in advance!!