craigls It looks like that attachment node is missing an input connection.
If you select the attachment and look at its upstream connections in the Node Editor, you should see two zGeo nodes connect into the iGeo1 and iGeo2 inputs respectively.
Here is an image that illustrates the case:
Additionally - if you look in the Ziva Scene Panel, the attachment in question should be listed under each body it is attached to.
If that connection is missing, the Ziva Scene Panel will not be able to properly update and an error should show up in the scriptEditor.
The easiest solution here, would be to select the attachment in question and delete it, then make a new one.
If this does not fix your problem, if you could then share your scene, I would be happy to take a look.
-jj