https://imgur.com/a/5vpF7b4

Having this issue as well :(

Just realized you and I were using the same texture pack. This happens with the unity texture pack installed. I removed the pack and it works fine. There may be some workaround using resource loader

For the mod author: to fix this you just need to include a copy of the original model and reference that rather than the existing one, in case resource packs overwrite it.

For the rest of us: Same thing, but use resource loader to overwrite Cathedral's files.