EDMCS subscription generates "<unknown>_Add" member?

In our development application (for an upcoming implementation) we're experiencing what appears to be a bug in a subscription.
We have a viewpoint that exists only to allow users to originate specific nodes that then flow to the Master viewpoint. We originate these nodes in a separate viewpoint so that we can auto-increment their names correctly.
When they subscribe to the target viewpoint, they're homed using a parent-finder (converter returns <unknown> for parent field and, on the target, the parent is calculated and stored). The subscription only allows ADD actions (no other filters).
When we add a new node on the source viewpoint, it commits on the source and the subscription adds it to the target perfectly. However, the subscription is also generating an extra add action for a node called "<unknown>_Add". The file attached to the request, when opened, shows no such record--it looks perfect.