Even though the fixture library claims that the JDC 1 is bundled with an A3D model, patching it in consistently loads the generic Tilting Bar model instead. Manually selecting the JDC 1 model produces different results depending on the fixture personality it's applied to.
It seems I was mistaken. Applying the JDC 1 model to a different fixture will attempt to fall back to the generic model, or modify the loaded model, such as messing up the position of submeshes.
I also noticed that there are a noticeable number of unused models in A3D's program files, whether they're labeled and bundled with an A3D model or not in the patch tab. This includes the JDC 1, the fos/4 Panels, the S4 LED Series 3, and more. I'm not sure why A3D doesn't load these models despite the files existing. As of v3.3.5.69, the error still presists.
