You might try backing them completely out of the minefield and then re-routing them through the breach. This worked for me with your savegame. I would also ensure you have no units with formations. Formations are for open terrain. Units will have a hard time in Korean terrain with formations.
Hmm... Tried backing out as you wrote; the Linebacker went trough fine but the Bradley was stuck again. And its path is right underneath the marked completed breaches. Both units had "no formation" checked.
Do you have a solution to my problem in ATF?
The marking for the breach is just a few pixels larger than the actual size of the breach, in order to make it more visible. To be safe, you should always try to traverse the center line of the breach.