In the "Help" section under "How do I interpret my scores/performance?", it says you can find your percentile rank (how you are doing compared to other people using UWorld as a percentile score) in the reports page. I don't have this, all I have is my percentage correct versus the average percentage correct. Does anyone else have this, or is this feature just not available for the MCAT version?

I only see percentage correct as well! I would guess the option is just not available for MCAT.