Error when editing existing media item

Problem/Motivation

When trying to change an existing media item, I get the error message "Non-reusable blocks must set an access dependency for access control."

This is for the drupal.be website - so might be related to i18n, although we have only set up 1 language so far.

This can be worked around by removing said block, and creating a new one with the new image, but that's a bit cumbersome.

Steps to reproduce

- Edit an existing page, e.g. Homepage.
- Try to change the media item used, by providing a new one.