I can’t translate the Plugin Reports Content

Please provide a link to the plugin.

Scratch that. I see that you already reported the issue to them here:
https://www.ads-software.com/support/topic/translate-problem-16/

I note you have the same issue using POEdit as you do using Loco Translate. This is because the problem is not the file editor.

The Report Content plugin doesn’t use its own text domain and doesn’t load any translation files. It uses only translatable strings that are part of the WordPress Core, e.g. “List View”. However, some strings are not in the core e.g. “Go to the first page”. For these you are stuck.

I recommend asking the author to properly internationalize their plugin.

Note that the WordPress community also say this plugin is not internationalized properly. See notice here: https://translate.www.ads-software.com/locale/en/default/wp-plugins/report-content