I saw this happen recently when my Inventory Service on the vCenter stopped due to insufficient disk space.
The first clue beyond the vCD deployment failures was the stopped Inventory Service reported in the vCenter UI, but looking at the logs on the vCD cell during the attempt to restart the Inventory Service showed multiple errors that vCenter was unable to write to its journal due to lack of disk space.
You'll want to look in /opt/vmware/vcloud-director/logs for the logs on the cell.