We are experiencing similar problems with Backup Copy Jobs, Rotated Media and Incremental Chains. (including Multiple VBKs some days and seemingly successful VIB Incrementals on other days, all from the same Job)
I have created a Support Ticket that is still outstanding from over 2 weeks ago (case 00731632). Each response that we have recived from Veeam Support has stated that Incremental Chains on Rotated Drive is not possible ... but this is not the results we are seeing. We are seeing that its does seem to be possible, if a little flawed!
Our last Veeam Support response stated;
"However this triggered conflict in a Veeam memory, for some reason backup chain was broken and we get mixed files in a repository one for January 20 and the second for January 26. Situation on the print screen was created by mixed of a different restore points for different time shifts, I am not even sure if this combination would be successful for restore.
Currently I see that algorithm which you are trying to use doesn't work like you need. Veeam doesn't support for each drive a single backup chain. It is a by design behaviour. Every time when a new disk inserted Veeam search for the latest restore point in a chain. We do not save for each drive an own chain, we think about all these drives like about one repository."
Obviously we are concerned the reported 'Successful' Backups may not be 'successful for restore' but we are also unsure about what is and what is not possible.
If you could you please clarify what is and is not possible , we would be very grateful?