Hey if you're exporting a rigged model from blender as an FBX for use in clip studio:
When you're exporting, scroll alllllll the way down to the bottom and make sure "Bake Animation" is unchecked. If you export it with "Bake Animation" checked modeler completely fucking loses track of the position of the mesh. I finally figured this out by trial and error after hours of fruitless googling.