Can't add tunnel interface created by restapi, to Security Zone using restapi.

[I.Miller]

Using restapi to create IPSec tunnels for a new firewall attached to Panorama. 

I create the tunnel interface using restapi. I can see the new interface successfully created in Panorama. 

When I try to assign that interface to a Security Zone it fails with: 

"Invalid Object:  Branch-VPN -> network -> layer3 'tunnel.781' is not a valid reference.  Branch-VPN -> network -> layer3 is invalid."

From Panorama I try to edit the security zone and add the interface but it isn't available on the drop down list.

If I open the tunnel.781 interface and click close from Panorama, the interface then is available in the drop down list and I can successfully run the restapi process. 

What is the web interface doing when you open the tunnel interface object, make no changes, then close it and how do I do it with restapi?