That's we understood, the tape device sends the information to Veeam about space. The customer is recycling a previously used tape with backup exec that's the reason we are enforcing a full format now before backup . It helps to reduce dramatically the frequency of not fully used tape to a couple in a 16 Tape set to one, max 2.
Case # 01705327
I know Veeam support planned to remote intervention with the customer, I checked the last job. It did not miss any tape but it was also much shorter.