I have seen this issue discussed here (or at least similar ones), and some suggestion that it is possible to resolve via a custom plugin (possibly using the GF set_post_values filter?) but I would be grateful for some further information if anyone out there is able to provide it. The issue that I have is that the theme I am using on a new project (ProReview) makes use of the WPAlchemy_MetaBox PHP class, which puts a whole bunch of the custom fields used by the theme into 2 arrays. I can see using this plugin that the standalone field created in the theme is visible and selectable when mapping a Custom Field to a form, but these arrays are not available to me.
Is anyone able to point me in the right direction as regards how I could have GF recognise these arrays too. Just a pointer even would be much appreciated, and might be of benefit too to some other users who are not seeing their custom fields to select.