Costumes can be loaded in base game without issue, but any that were created using mods prior to using patchwork don't load modded costume parts.
Costumes saved in editor, even when created using Patchwork, do not load when loaded into studio.
It should be noted I'm also not using the most recent release of koikatsu (explaining why I can still even use Patchwork), have Bepinex 4.1, and Bepinex plugins 5.1
Attempting to load an outfit onto a character in CharaStudio removes all clothing instead of applying the correct costume.