Try these steps and see if it works for you:
- Remove the Unborn Val'kyr from your NPCScan list.
- Log out and turn off NPCScan (from your character selection addon screen).
- Log back in and make sure the "uncollected" pets are checked off in your Pet Journal.
- Log out completely and delete your Cache folder.
- Re-enable NPCScan from the character selection screen.
- Log in and add the Unborn Val'kyr to the list.
- If it continues to show as marked off, log out completely and delete your Cache folder again.
This worked for me but it should be noted that not everyone has had success with adding the Unborn Val'kyr to NPCScan.
Are you using any other addon that might cache your pets (collected and uncollected)? Other addons that log your pets might be interfering and causing a false positive scan each time you log in.