
Here I just imported female_clothes_secular_fp1_common_01.mesh into blender (settings: import mesh, join materials, import skeleton, import locators) then immediately clicked save mesh (settings: export mesh, export skeleton, export locators). If I click "split all vertices" on the export, it looks even more spiky and messed up.
If I follow the same steps for a different file, female_clothing_secular_indian_nobility_01.mesh, for example, the model doesn't load at all and the character shows up naked. The vast majority of the clothing meshes I've tried importing/exporting end up disappearing rather than showing up spiky.
Even though they are messed up inside CK3, I can re-import the meshes and they look fine in Blender.
The blender log doesn't display any errors - it shows "finished importing" and "finished exporting" from io_pdx_mesh.
I have a few mods enabled but I don't think they should be interfering with this considering everything displays fine before the export. I can take more screenshots but I don't know what info would be helpful. I wish I could compare the files before/after. I'm curious to know how the file is changed by the export.