Cancelling addition of new content puts random reference into list

I have for several content types a field with multiple node references. When adding a new reference with "new content", a selection list for the referenced node type appears, where I can choose among the allowed content types for this field.
When i cancel there, I am taken back to the form, but the reference I just wanted to create but cancelled is not empty as I would expect. Instead there is a reference to a random node, quite often [nid:1], sometimes even of an unsupported content type.
This leaves the form in a state where it (without removing the new entry) either cannot be saved or saves an unwanted reference.