permissions on search filters selectable values - a bug?

Good morning,
I have this situation:
[LIST=1]
[*]a custom record "customrecord_1"
[*]a custom record "customrecord_2", with a custom field "custrec_2_1", with these properties:
[LIST]
[*]Type = "List/Record"
[*]List/Record" = "customrecord_1"
[/LIST]
[*]a role that has "edit" permissions on both "customrecord_1" and "customrecord_2"
[*]several partners with the role above
[/LIST]

When a partner creates either "customrecord_1" or "customrecord_2" records, the other partners with the same role cannot see his records in the list pages.

But when a partner performs a (advanced) search on "customrecord_2", and in the "criteria" -> "standard" tab selects the filter on the "custrec_2_1" field, the selectable shown values are all the records of the "customrecord_1" record type, including the ones made by other partners.