I installed by myself my purchased copy of Unlimited PHP... (very easy to do... I'm not an expert...) with all the permissions correctly set.

It works if I run it manually but, after about 5 minutes, it stops displaying like shown in the below image...

Seems that runs on steps, and then stops. Where's the problem?

Sitemap.xml always remains  "empty" at 0 bytes

(see the attached image)

THX
Hello,

it looks like your server configuration doesn't allow to run the script long enough to create full sitemap. Please try to increase memory_limit and max_execution_time settings in php configuration at your host (php.ini file) or contact hosting support regarding this.