People are having weird issues with my stages. Right now, Rock Wall and Stadium were built off of Hyrule 64 but ported to other stages (Pikmin and Boxing Ring respectively). When you port a stage to another slot, the two stages kind of overlap, so you need to delete and edit out the original stage so that only yours remains.
What I've seen is that, apparently, some people's systems aren't loading the deleted / modified files I made for Boxing Ring and Pikmin. I have no idea what's causing it, but I'm chalking it up to user error (not having the correct Luma 3DS settings, not being on Salty SD, and possibly not using Smash Selector).