Hi. I may have found a bug related to the gallery field.
I’m running WP 4.0 with the last version of ACF PRO (5.0.8).
I have a gallery fields that works perfectly on my local site.
The live site has the same configuration but all the custom fields are generated from a php file that contains the export from the local version.
This cause a problem with the gallery field. The images are showed correctly on the front and backend but the information panel in the backend in empty.