Images empty when editing products using inline entity form

Confirmed, it is an issue with...

    // Attach fields.
    $langcode = entity_language('commerce_product', $product);
    field_attach_form('commerce_product', $product, $entity_form, $form_state, $langcode);

on a multilingual site. If there is a check for $langcode being empty and setting it as LANGUAGE_NONE; it fixes the issue. For some reason the Image field doesn't populate properly on the entity edit form unless $langcode is explicitly set.

Moving this to inline_entity_form, patch to follow.

Apply a fallback to set language code to undefined if entity_language empty

The same issue here, but the patch did not work for me!

This looks like a revert of #1558632: Pass correct langcode to field_attach_form, newly created entities. which means we need more research on which one's correct.

The above patch does not include a fix on the default entity form.

Patch attached.

Got the same issue with a custom entity (not a commerce product) and this patch solved the issue for me. The images are now visible in my field using IEF, FYI here is a summary of my setup:

1. the field with IEF widget is translatable through Entity Translation
2. the entity referenced by IEF is not translatable (my strategy: different entities per language)
3. the IEF widget is the "Single value" one
4. my entity type has been created using Entity Scaffold module.

Would you like me to test something more on my implementation?

Thanks for the patch

Patch #9 from the referenced issue solves this problem at a higher level, with entity translation support instead of hardcoded LANGUAGE_NONE.