Why is this excav circling all the way around to mine that tile? (save incl.)

Strange behaviour of pathfinder? No?

Where is the tower in relation to this?

To the left, you can see it.

Looks like it is moving to the side closest to the tower? Not sure where it was coming from before, but they will do their best to approach work from the side closest to the tower if they have had to move very far from their last dig square.

It’s circling to the right

So trying to go up and dig it from the far side?

It should be approaching from the left, but it's circling to the right.

I just included the save and didn't bother to explain too much - it's not important but I thought they'd appreciate it if it unveils some weird quirk of the pathfinder.

I'm very familiar with the fact that excavs choose targets based on the position of the tower, and often move towers to ensure excavs don't trap themselves while making folding ramps. But this is unexpected behaviour even for me.

It's not difficult to avoid the actual problem of excavs constantly changing sides - I just cut off the right side so the ramp was only accessible from the left, and it mined from the left like it should until there was only one tile left. But this still feels like unintended behaviour, even if it's not really problematic.