I had the same issue when we did our LM to vCD migration. In our case it was something to do with the network settings on the VM's from LM we exported to OVF.
We didn't like the export from LM to vCenter, export from vCenter as OVF, and then import to vApp process either. What we ended up doing was exporting from LM to a swing LUN that was connected to both environments, remove from LM vCenter, attach to vCD vCenter, clean up VM (attach to valid network, update OS type (as we had some RHEL 6) upgrade VMware tools, upgrade VMware hardware, etc...), then create the vApp, import VM's from vCenter, and connect VM's to vApp Network. It's a long, complicated script but the VM's were cleaner when done.
-Eric
