While the Backup Set view is in a "Loading” state, the lower left the Backup Exec console displays a Backup Exec console Query Status of: “The user interface is waiting on 2 calls to the Backup Exec Server”.
Debug the Backup Exec UI console reports a QueryBackupSetResource failed or an Exception after an extended amount of time (Figure 3). How to Debug the Backup Exec Console thru the Debug UI Tab
Figure 3

Under Investigation. This issue may occur due to a large amount of Backup Sets.
WORKAROUND:
Use the restore wizard to view the Backup Sets.
This issue is currently under investigation by Veritas Technologies LLC. Pending the outcome of the investigation, this issue may be resolved by way of a patch or hotfix in current or future revisions of the software. However, this particular issue is not currently scheduled for any release. If you feel this issue has a direct business impact for you and your continued use of the product, please contact your Veritas Sales representative or the Veritas Sales group to discuss these concerns.
Figure 2
From the Backup/Restore tab right click Restore or using the Restore wizard the Backup Sets ar visible to restore from.