level 5 pipes causing partial pathfinding issues

works for most of 80 trucks, but 3-4 trucks get an issue saying they are struggling to find a destination when there is path under level pipes as well as paths around it

This sounds like a throughput issue, where multiple trucks are trying to reserve the space simultaneously. Did it only start occurring with many trucks? Do you recall the threshold if so?
Is the area in question a very high traffic area? (IE a bottle neck)

I suspect the devs will request a save file for this one.