VMware restore from VMFS3 to VMFS5

Every time I try to restore a VM that was backed up when it was on VMFS3, to a new VMFS5 LUN, the restore completes fine, but I cannot boot up the VM. I tried to mount the VMDK on another server and read it, but it says disk is corrupted.

Is anyone aware of a bug or a known issue?

This is NBU 7.6.02

the backup was done on 7.5.05

thanks,