It’s possible that I tried these steps in a version that wasn’t 5.1 by accident last night without paying attention to that particular detail.
I’m investigating the solution for 5.1 specifically (as documentation is not clear on what causes that option to be greyed out). Though in the meantime this should not cause an issue when following the course.
Edit: Looks like the steps I outlined were introduced in UE 5.2 and that the ability to disable World Partition once it’s enabled for a level (which is the default for the levels used in the Third-Person and First-Person projects) is not possible in 5.0.3 and 5.1.1. However, you can create a new blank level without world partition by going to File -> New Level -> Blank
.