Attachments not being added to custom field

Hello,

I have a custom post type called ‘Film’ in one network site which I’m broadcasting to other network sites.

On this CPT I have an ‘image’ advanced custom field (set to ‘attach to post’). When I broadcast a film to the other network sites, the ‘image’ fields are empty on the new posts. However, I can see that the attachment has been copied across (I can see in ‘Select Image’).

Any idea why the attachment isn’t being added to the corresponding field?

Thanks.