I am trying to extend "See own Leads" Group with another rule for the Partner Object. In Sales Module, Customers section, only special partners dependent of this rule's domain filter should be listed. For these customers, all users with this group assigned, should have full access rights.

Domain filter works: Only selected partners are listed. But when trying to write on the records (edit or update), an error occurs:

Access Denied The requested operation cannot be completed due to security restrictions. Please contact your system administrator. (Document type: Partner, Operation: read)

Could anybody tell me, what else needs to be configured to obtain full access rights for all the  listed partner records? How can I get rid of this error?

Please see attached the rule I extended the "See own Leads" Group with, what caused this error.