This is an interesting point about the levels. I looked at a random thread and checked whether I could see the profiles of the users in that thread. As far as I could tell, it looked like anyone with a profile below level 26 was accessible, and anyone above 32 was inaccessible (with the exception of users who are not active subscribers, whose profiles work but show up as level 3). It does seem possible that this issue only occurs once you get past a certain level.
I found a level 31 user whose profile loads and a level 32 user whose profile doesn’t load, so it seems like the boundary is roughly around there - I wonder if there’s a specific item on level 31/32 that breaks things.