Non-admin users get "Integrity constraint violation" error

First of all, thanks for this great module: it is a pleasure to use!

I have run into a minor problem that occurs when a non-admin user tries to edit for example:

http://fmysite/admin/structure/entity-type/asset/asset/1/edit

When he/she saves the form, the following error occurs:

PDOException: SQLSTATE[23000]: Integrity constraint violation: 1052 Column 'nid' in where clause is ambiguous: SELECT DISTINCT node.nid AS entity_id, node.vid AS revision_id, node.type AS bundle, :entity_type AS entity_type FROM {node} node INNER JOIN {node_access} na ON na.nid = node.nid WHERE (nid IN (:db_condition_placeholder_0)) AND (type IN (:db_condition_placeholder_1)) AND(( (na.gid = :db_condition_placeholder_2) AND (na.realm = :db_condition_placeholder_3) )OR( (na.gid = :db_condition_placeholder_4) AND (na.realm = :db_condition_placeholder_5) ))AND (na.grant_view >= :db_condition_placeholder_6) ORDER BY node.title ASC; Array ( [:db_condition_placeholder_0] => 19 [:db_condition_placeholder_1] => mena_case [:db_condition_placeholder_2] => 0 [:db_condition_placeholder_3] => all [:db_condition_placeholder_4] => 1 [:db_condition_placeholder_5] => view_unpublished_mena_case_content [:db_condition_placeholder_6] => 1 [:entity_type] => node ) in EntityFieldQuery->execute() (Zeile 1136 von /var/customers/webs/ICAR/forum/Server/includes/entity.inc).

Notice that the problem does not occur when logged in as administrator. I have tried enabling (for this user) all permissions under the "Entity Construction Kit" permissions category, but this didn't help.

Does anybody know where the problem might be?

Thanks for any feedback and hints,
Kaspar