Get multiple results from entity reference relationship in views
Verify Distinct Checkbox in View Query Settings. You should disable it.
Verify number of items to display is more than one.
Make sure no filters or contextual filters added that will effect the view results.


I just added a entity reference field to Article Content Type. And then added a relationship to the entity in view using Relationships. It does show multiple values.

I am not sure what other configurations are enabled in your view. See below query generated using views for above scenario.

SELECT node.title AS node_title, node.nid AS nid, users_field_data_field_user.name AS users_field_data_field_user_name, users_field_data_field_user.uid AS users_field_data_field_user_uid, node.created AS node_created, 'node' AS field_data_body_node_entity_type
FROM 
{node} node
LEFT JOIN {field_data_field_user} field_data_field_user ON node.nid = field_data_field_user.entity_id AND (field_data_field_user.entity_type = 'node' AND field_data_field_user.deleted = '0')
LEFT JOIN {users} users_field_data_field_user ON field_data_field_user.field_user_target_id = users_field_data_field_user.uid
WHERE (( (node.status = '1') ))
ORDER BY node_created DESC
LIMIT 5 OFFSET 0