Parent node is not valid through subscription

We are trying to update a viewpoint through a subscription request but getting an error.

"Parent is either not a valid node in node type '', is valid and not the parent, or the parent's node type doesn't exist."

We can see the parent node in the viewpoint that is receiving the subscription updates, so we are unsure as to why the parent is appearing as invalid.

I have also included the regex for the transforming of the parent node.