Blank modal when trying to delete an attachment

[GuyonWoW]

Joomla 3.8.8
Attachments Version 3.2.6
PHP Versione and server details: http://webs3.apkappa.it/pi.php

Whenever i try to delete an attachment from the frontend side i see a blank modal window.
Editing an attachment works.
All the operations from the backend works.

I tried to reinstall it, i tried different joomla versions, nothing seem to fix it.

Any idea?
Thank you.