Backup Exec 2012 - Backup Jobs Stuck in Queued status randomly

BE 2012 created 3 backup jobs to backup VM to deduplication storage. 3 Backup jobs are schedule to run at the same time. These backup jobs sometimes can be ran successfully. But these backup jobs randomly stuck in queue status over 10 hours , so that nothing can be backup.

Then I want to cancel these backup jobs but failed to do. The status is still queued, not change to "cancel pending". Finally, I need kill begine.exe in task manager and restart all BE serices / reboot BE server.

BE 2012 has been fully patched (include the lastes hotfix 201596). All VM has been installed the lastest version of remote agent.

I found Symantec KB similar to my case. (http://www.symantec.com/docs/TECH159843) 

The solution:

Using the regedit tool, edit the following key:

1. • Key Name: HKEY_LOCAL__MACHINE\SOFTWARE\Symantec\Backup Exec for Windows\Adamm
   • DWORD: Enable OST Space Reclamation
   • Value: 0
2. Restart Backup Exec services.
3. Run the jobs that need to be run.
4. Change the value of the Enable OST Space Reclamation DWORD to 1 to enable it again.
5. Restart the Backup Exec services.

But this KB is applied for BE 2010. Can I apply the same solution  on BE 2012?

Do anyone know the solution?

I have open Symantec support ticket over 2 weeks. But they still not find the solution.