Hey Craig -

Without you providing addt’l details...I assume you’re doing a File Backup of S3? (i.e. unstructured data backup)? Not tried unstructured backup of AWS S3, but in looking at some requirements from the Guide...just a few things to verify → are you on v12.1 at least? 
https://helpcenter.veeam.com/docs/backup/vsphere/platform_support.html?ver=120#unstructured-data-backup-support

And, do you have a Cache Repo set up for the Job?

Correct , unstructured data backup, definitely on 12.1.2.172 and yes have cache repo setup. it’s a strange one

Ok. Hmm...to this point, I have not seen anyone post a question on here about this issue. 

In the Job, when you select your Bucket...are you able to expand it to see the objects there as well like you can when listing them via PoSH?

https://helpcenter.veeam.com/docs/backup/vsphere/os_backup_job_objects.html?ver=120

If so...I’m out of suggestions myself. Probably best to work with support on this one...unless someone else chimes in.

yeah thinking this is a support worthy issue. I don’t see the objects like the kb article you listed. Just hoped someone else had encountered this. Cheers

No problem...sorry I couldn't help further. I'd be curious to hear what Support finds. 

Only other thing that came to mind is the account used isn't able to "list" the S3 contents. But, if you used the same account in the PoSH screenshot, it appears the account is ok.

Does the job show the folder Demo_Files in the bucket when your create it @Cragdoo ?

nope :(

Title says it all, attempting to backup AWS S3 bucket, have confirmed bucket does contain data,
 

but when the backup job runs

 

 

Any ideas?

Fixed it ...when I added the unstructured data to the Inventory, I picked the wrong Data center .. I picked US East (N.Virginia) instead of US East (Ohio). Strange thing is Veeam didn’t throw up any errors. Got there in the end ...phew

 

Good find @Cragdoo ! Glad you got it sorted