Hey Claudeir,
I am sorry for some confusion in earlier, regarding with your initial issue, i believe my colleague missed up point out that issue only happen on when Easyblog perform an ajax call from your site to your server instead of your frontend blog post URL.
By default, when the Easyblog perform an ajax call to request something (e.g. get those media data from your server) from your server, it will call this similar URL :
[gist type="php"]
http://site.com/?option=com_easyblog&lang=&_ts=1510153631103
[/gist]
For some reason your server restricted this but your server accepted this if included index.php e.g.
[gist type="php"]
http://site.com/index.php?option=com_easyblog&lang=&_ts=1510153631103
[/gist]
By the way, we have a few customer encounter this issue in previously and this is not server issue actually, in order for us to make it work for certain server which restricted this, so we make it as an option in Easyblog 5.x onward, so whoever having this issue, they can just enable this setting as what my colleague mentioned in earlier (screenshot :
http://take.ms/ohjQF ), so those ajax call will work just fine.