G'day. I've had and solved this issue. Time for some minor registry hacks.
Instead of me retyping it all, go to <>.
Basically, if you've got the same issue I had (which it sounds like), the section on "Backup Exec for Windows NT v8.x" and the sub-section "Insert Media Prompt Response".
Basically, I narrowed it down to the drive and BE not timing out at the end of proceedings like it should. This forces it to only wait 30 seconds (or more if you chose but I say stick to 30) before moving on to the next step which in this case, is going back and waiting for the next scheduled job to kick in at the proper time.
Hope it helps.
Now back to hunting for help for my own current problem. :-)>