Truck struggling to reach excavator even when it's right there

Trucks seem to have some mysterious extra requirement for considering an excavator to be reachable. Image clearly shows that the terrain between the truck and the excavator is navigable, and in fact I've manually directed the truck to drive right up to the excavator -- easily close enough for the excavator to unload into it, normally. But the truck just goes to wait by the tower.

More aggravating/mysterious: after manually moving the excavator a couple of times (repositioning it slightly and also taking another scoop out of the terrain) it got to the point where the trucks could reach it. And lo, the trucks didn't drive anywhere near as close to it as I has positioned the truck in the previous screenshot.

Issue recurs a few moments later, even though the excavator is in virtually the same position as before, and its digging hasn't made anything less accessible. Something about this pathfinding is just weirdly chaotic. Save attached.

there could be a height difference that is causing the truck to "refuse itself access" (usually due to land fall/land slides under the excavator) and the pictures or your view of the situation/access heat-map are a visual distortion of the actual situation. I would wait for the devs to way-in anyway

the truck is obviously not at a similar height to the excavator - I assure you, that in real life, this situation is also impossible for the excavator to be reachable by the trucks...

you would need to create a more gradual incline for the trucks to be able to have a stopping position for the excavator to put it's load in them... ( how did you get that excavator there, anyway ?)