Hi @<1654294820488744960:profile|DrabAlligator92> ! The way chunk size works is:
the upload will try to obtain zips that are smaller than the chunk size. So it will continuously add files to the same zip until the chunk size is exceeded. If the chunk size is exceeded, a new chunk (zip) is created. The initial file in this chunk is the file that caused the previous size to be exceeded (regardless of the fact that the file itself might exceed the size).
So in your case: am empty chunk is created. file1.npz is added to the chunk. The size is not exceeded. Then file2.npz would be added to the same zip, but the file is too large, so the chunk size would be exceeded. A new chunk is then created, containing file2.npz