can you elaborate on the following:
Which host is each VM running on, including the Edge device for the Org Network? it may just be luck that some VMs are on the same ESXi host as the Edge Device. If this is true, the ones on the same host as the edge work, then your host spanning is not working.
What type of Network Pool are you using for this Org vDC? This is the isolation method used to facilitate a isolated spanning network. If you are using VCDNI, make sure that the VLAN exists on the physical network fabric, and you have an MTU of 1524 or greater. If it's VXLAN, make sure it's setup and configured correctly. If it's vLAN backed, make sure all VLANs assigned to the pool actually exist on the network.