The expected behavior for "Multi User from other User" field is :

• If Link parameters are not defined, the User Fields are read from current Issue
• If Link parameters are defined, the User Fields are read from linked Issues

Linked Issues are identified by :

• Issue Field in current Issue (if not Link Type or Linked Issue Type are defined)
• Or among any Linked Issues that matches with expected Issue Type (when no Link Type is defined)
• Or among Linked Issues that matches with expected Link Types