Ok, you've find a bug in the contrib. The problem here is that the user running apache (www) doesn't have read access to the share. Historically, it was only possible to set permissions on groups, so, as long as one group had read or write access, user www (which is a member of every groups) also had the same access. Now that individual users can have different permissions, I need to explicitly grant www user access to the share.
Waiting for a fix, you can grant at least read access to any group you want, and web access should then work.
Regards, Daniel