I send a message to the OMS with the HIN. OMS sends a message to the car on either side in the lineup and asks those drivers to look for the HIN. 9 times out of 10, that solves it.
I never used to send in 'cannot find messages' until someone posted a similar thread 2ish years ago. There was something in that thread about CYA and all that, so I started sending in a message. It has gotten some misloads found early enough in the day that we made service on them. It is a pain in the rear, but whatever.