So I want to extract some Sims, and I opened SimPE. I loaded the sub-hood I wanted, and opened SimSurgery, but it never loaded the Sims. I tried clicking on an option so that I make sure it hadn't freezed, but it hadn't. It was just not loading the Sim list.
I saw an old thread like this one here, but the user installed another version of SimPE and got it fixed. I have the most recent one so I'm not sure if this is the problem?

I tried reopening it again but the same issue occurred.

Edit: I just realized I'm an idiot. You need to open the neighbourhood even if the Sim is in a subhood.