using endpoints in Rules does not work

Steps to repeat:
1. Install the relation, relation_ui, rules and rules_ui modules.
2. Create a Relation 'has page' from User to the Basic Page content type.
3. Go to admin/config/workflow/rules/components/add
4. Add a Rule with one parameter 'relation' of type 'Relation'
5. Add a Condition: Entity relation is of Bundle 'has page'
6. Add a Condition 'Data Comparison'. Select relation:endpoints:1:

Expected Results:
Rules should know that endpoint 1 of the Relation is a basic page, so I should be able to select the body field.

Actual Results:
There is nothing to select after relation:endpoints:1:

If I install the entityreference module and add an entityreference field referring to basic pages to the relation, that works fine - I can do a data comparison for relation:field-page-reference:body:value to my Rules.