To be clear, I already said that chunked uploads and "Immediately upload each part"
will not work together correctly in Akeeba Backup versions before 7.0.0. As I said, it is an architectural issue that could only be fixed after doing several rounds of refactoring which eventually culminate in version 7 which, at the time of this writing, is not yet released.
The type of backup is irrelevant to this issue happening with the currently released versions of Akeeba Backup. My suggestion for a more efficient way to back up your site was made on the premise that "Immediately upload each part" would be disabled.
However, this is a moot point if you're willing to test a pre-release version of Akeeba Backup 7. Please give
version 7.0.0.a1 a try. I have already tested it with a big, multi-part backup being uploaded to Amazon S3 in multiple chunks. Version 6.6.1 failed to work properly, as you reported. Version 7.0.0.a1 worked. If possible, please test your backups. I have not seen any issues restoring the backups but I'd appreciate feedback from more people except yours truly and my associates :)
Nicholas K. Dionysopoulos
Lead Developer and Director
π¬π·Greek: native π¬π§English: excellent π«π·French: basic β’ π My time zone is Europe / Athens
Please keep in mind my timezone and cultural differences when reading my replies. Thank you!