The images are shown in the table nicely, but after clicking edit, the imagefield contains no images.
This can be seen in:
The reason for this is that IEF is now calling the field attach form with the proper language code.
However, the demo store products have no language code assigned ($product->language) is empty, which confuses the language fallback.
The solution is to set LANGUAGE_NONE as the language to each product during product creation.