Excavator goes straight up cliff

Issue description

repeatable bug: excavator goes straight up cliff
video of this behavior: https://www.youtube.com/watch?v=1TnJY5C5SWY
Screenshot of same behavior happening at a later time:

Note: attached save is actually a third example of this happening at the same location

Expected behavior

excavator shouldnt be able to climb a cliff

Reproduction steps

1. Load attached save. Location of repeatable issue is focused on.
2. Excavators here digging at the bottom of the cliff have caused dirt to fall down, which causes the excavator to be unreachable by the assigned haul trucks (possibly related: Excavator digs ground into a shape that makes it inaccessible to trucks)
3. Excavator was assigned a new location to move to. Note: the location was assigned, and the excavator started climbing the cliff before the attached save was made.
4. excavator travels up the cliff instead of going to the location.

to repeat the issue: the second excavator in this area also exhibits the same behavior. It is unreachable by the haul trucks, and climbs the cliff if given a manual location. This is repeatable in the attached save file after multiple reloads, and happens regardless of where the manual location is set to.

Game version

0.4.13 (148)

Attachments

excavator goes straight up cliff.save

Files not imported: excavator goes straight up cliff.save

I'm also experiencing this with 3 excavators that I told to go one tile over, and instead they are climbing the cliff in the opposite direction, all three of them.
My game version is v0.4.14a

I also am in a spot where they are digging up a ramp, and got to a state where none of the trucks can get to them, in spite of them being in a green transport area. This is why I told the excavators to come back down the ramp one tile as this usually fixes the broken trucks.

Very similar circumstances to @tippyc2 [github] (like.. identical lol :-P )
I can also provide a save file if requested

Screenshot for reference