The Rotate IP feature can be enabled in the project's Settings tab, and is exclusive to premium ParseHub users. Unless you have a reason, don't turn on IP Rotation. If you aren't certain, Contact Us to have a look at your project.
This feature should not be always enabled. In most cases, it will slow down your runs without any benefit.
When you should use IP Rotation
Sometimes, if you get an empty results file despite your Test Run working, this could be because the website is blocking ParseHub's servers.
You can check if this is happening by using the Server snapshot feature on a few templates.
When a run is finished, you can see the snapshots that the server takes of what it 'sees,' at each point in the run where you add the command. These are found on the Run page.
If you get a screen that looks something like this, or with a captcha in a server snapshot, this means that you may need to turn on IP Rotation.
If this still fails to fix the issue, you might need to add wait commands at various points in the project, especially between click, hover, scroll, and go to template commands. Anything that interacts with the page is likely to be noticed by IP blocking scripts.