I recently had the requirement to backup the data on a cifs file structure (shares on a netapp filer).
To catch all files, I needed to use an account with permissions on the whole file structure.
Therefore I changed the logon credentials of several of the Veeam Services to this special service account. (Veeam Backup, Data Mover, ...)
But I didn´t change the logon credentials of the "Veeam Installer" service, which stayed as "local system".
(I thought this service - from the name - would only be used for the components deployment...

Result of that setup was, that the job started and finished immediate. (with Successful result!)
In the log I found - "No new files to backup per job settings" and a system exception like this only in the log files:
Failed to get item info for \\xxxxx\yyyyyy (System.Exception)
Error Veeam.Backup.ProxyProvider.CProxyFileCommander.GetFsItemInfo(String itemPath)
After also changing the credentials of the Veeam Installer service to the user with permissions on the shares, the File to Tape Backup worked.
Maybe that should be mentioned in the documentation somewhere or the name of the Veeam Installer service changed into something reasonabler.
Some useful logfiles where there is more useful debug information according f2t jobs:
Svc.VeeamInstaller.log
Svc.VeeamInstallerDll.log
Some words to the performance of File to Tape Jobs with v9.
Average Job Throughput of ~~ 40 Mbyte/s on a file structure with: (1 TB data; 700.000 Files)
So a great improvement to v8.
Another hint according netapp cifs backup - why not backup the .snapshot\daily.0 on netapp shares instead of the share itself. No open file troubles anymore.
Greetings,
Manfred