UnitOfWork saveRelatedLocalKeys() creating erroneous child/parent rows

 
---
Staff:
  columns:
    username: string(50)
    password: string(255)
    active:
      type: boolean
      default: true
  indexes:
    user_pass_active_idx:
      fields: [username, password, active]


Tickets:
  columns:
    mask:
      unique: true
      type: string(10)
    staff_id: integer(9)
  relations:
    Staff:
      local: staff_id
      foreign: id

 
<?php
$ticket = new Tickets();
$ticket->staff = null;
// This save generates the NULL record in the staff table
$ticket->save();