I have a form where one field of checkboxes is pre-populated with the contents of some posts (CPT "book").
This works perfectly and in the frontend as well as in the back (edit area) I see all the fields (see screenshot http://l.uprise.nl/mnwdc ).
One problem however, I've added a new book ("Cloud") lately. I see it in the frontend, but I don't see this one back in the selectbox of the merge fields (screenshot: http://uploads.uprise.nl/Screen_Shot_2012-07-18_at_15.07.18-20120718-150805.png). There are 5 books, but not "Cloud".
Also when I dump the data of the $form object I see the "choices" are filled as it should be, but the "inputs" array misses the "Cloud" item.
What can this be, and how can I update this "inputs" field, since just updating this array in the pre_render filters doesn't seem to work.