I hate bringing this up after you've copied all that
data, but the problem is that the partitioning scheme on your
destination disk is wrong. CCC would have warned you about this the
first time that you backed up to that volume, but wouldn't have
prevented you from using it as a destination (not everyone wants to
boot from the backup).
To solve the problem, you'll have to repartition the destination
disk using Disk Utility. I explain exactly what you need to do here
in the documentation:
You can back up to a flash drive. Again, the disk has to be
partitioned with the GPT partitioning scheme (most ship partitioned
with the "FDisk" partition scheme, or Master Boot Record), but you
can do that. Have some patience, USB "disk on key" or "thumb
drives" are quite a bit slower than ordinary disk drives.