About the contents of the archives

Sometimes there is some models’ metadata downloaded from api with empty archives. Is that means it’s not downloadable and can’t supply an archive? And it really confuses me that, is the ‘source’ field in archives means the original file format? Then why in some models, the FaceCount in ‘gltf’ field and ‘source’ field contradicts with that data in json file (in the ‘result’ field)?
I think there may be some mistakes in my understanding (but I don’t find it in doc), and I can’t point it out. Hope for some direction and thank you.

Can you share a link to a 3D model where you are experiencing this issue? (And the API call response if you have it)