Some of the S3 dump files are 0 bytes (weird?), and after they are imported to Metis, they cannot be found by API (specifically bulk_copy) even though they have database entries and appear in the Metis UI. Since they cannot be found (they point to the 0 data_block), they cannot be removed via the UI or otherwise copied...
Expected behavior is that 0-byte files can be removed via the UI / API, and maybe even be copied if so desired?