Ok I have looked into it, and found out what the problem is. It's almost a bit embarrassing. In last release, I added some X3-compatibility to Files app, so that it can be used as an optional control panel when X3 is in the parent directory. In your case, Files app is detecting X3 in the parent directory, so it tries to use X3 pre-created thumbnails, yet the images you are trying to view remain inside the /thewall/ folder. This means we are getting wrong image-resize links like this:
https://www.melegnanofotografia.it/render/w480/anp6503.jpg
That image is inside /thewall/, but the X3 resize script is trying to resolve it from inside your X3 /content/ dir, and it doesn't exist there. ANYWAY, I will have this fixed shortly. In the meantime, you can fix it by opening Files app index.php
and locating around line 264:
// X3 compatibility / x3 login / images from X3 resize cache / invalidate X3 cache on filemanager op / X3 license
$x3_path = dirname(self::$root);
self::$x3_path = file_exists($x3_path . '/app/x3.inc.php') ? $x3_path : false;
if(self::$x3_path && self::$username === 'x3'){
$x3_config = file_exists($x3_path . '/config/config.user.json') ? json_decode(file_get_contents($x3_path . '/config/config.user.json'), true) : false;
self::$username = isset($x3_config['back']['panel']['username']) ? $x3_config['back']['panel']['username'] : 'admin';
self::$password = isset($x3_config['back']['panel']['password']) ? $x3_config['back']['panel']['password'] : 'admin';
if(self::$username === 'admin' && self::$password === 'admin' && isset($x3_config['back']['panel']['use_db'])) error('Sorry, Files app is not compatible with X3 panel database login. Assign "username" and "password" separately in _files/config/config.php.', 403);
}
Just remove all the code above! Then your Files app will ignore X3 as the parent dir. Your issue should not be related to PHP version.