I’m using the free version of ACF 4.4.11.
Only one rule for a field group is exported/imported.
If you have more than one rule, you need to add them manually.
I just did a test on ACF4 and the export/import seems to be working for me. Try deactivating other plugins and maybe switching themes to see if you can find what might be interfering with the export/import on your site.
Thank you for testing and answering.
I’m using the plugin WP Re-Importer for importing contents. If I use WordPress Importer all rules are imported correctly. So it’s not a bug in ACF but in WP Re-Importer.