Most of the time the convoys are above ground.
Without fail, EVERY resource convoy spawns 'incoming reinforcements' from underground. I posted a screenshot of the last failure. This was the third convoy in extremely quick succession.
1. ELITE - all reinforcements fail to materialise. Thus, No success, no resources
2. Normal - successful
3. Normal. - (screenshot) no reinforcements, no resources, no completion.
I have ALWAYS had problems with the convoys around this area. The enemy spawn from below and most of the time not all of them come to the surface...or not all of them spawn...or come to the surface. If would be great if you coulds alter the logic to fix the spawn points.