"Create Bag on object modification" should be turned off during batch ingest, because when each derivative is finished generating, a new bag is generated...
Example I have witnessed and can attest to:
1. Generate TN
2. Bag is generated
3. Generate MEDIUM_SIZE
4. Another bag is generated
5. Generate JP2
6. Another bag is generated...
When big data objects are in play, this bug becomes a system killer...
To cope with it, I turn off the option programmatically, prior to beginning a command-line ingest:
drush vset islandora_bagit_create_on_modify '0'