"Unfortunately, the only possible solution is to perform erase of these tapes with native HP Tools"
This is bad, i will need to manually shutdown veeam services, Open HP LTT (which will lock the drive) then insert Tape 1 , do a Quick Erase, Shutdown HP LTT start Veeam Services
rescan tape drive since it lost the Connection to the Tape Unit when HP LTT used it, run Tape inventory and this i need to do every day in 2 weeks since the Customer Changes tape once a day. And Clearing 2 weeks of tapes in one batch isn't a good option since we then looses 2 weeks of backup history if we need something back.
A simple powershell script just erasing the Tape and scheduling this Before the Tape Backup Job should just solved this issue.