I doubt it's a UEFI or SecureBoot problem... the Fedora Live USB I made boots just fine. The UEFI setting is EFI-only (no legacy boot). I also tried with and without SecureBoot, and had the same behavior. (Interestingly, even with SecureBoot turned on, I did not have any issues installing and booting Fedora if I removed all the existing partitions. I didn't actually expect that to work and still not sure why it did.)
To be clear, the problem doesn't occur at boot time. Rather, Anaconda appears to lock up before it begins creating the partitions I specified and installing packages.
So, I'm willing to bet it's more of an Anaconda problem. I'm just not sure how to even begin tracking it down. I had thought it may have something to do with the extra recovery partitions, but the partitioning screen in Anaconda seemed to detect the existing partitions just fine.