Trucks are stopping, stuck

Issue description

For some reason my trucks and excavators are stopping and saying they can't reach a destination (their Mining Control tower usually). This started during the previous small patch (v 0.5.1 or v 0.5.1a)

Expected behavior

Normally trucks just return to the tower and then get on with another job. Now they are stopping and reporting they cannot reach a destination, and will not restart until I click the bullseye (manual drive icon?) and click anywhere. If I click next to the tower in question they drive up to it, stop, and assume a new job. (unless they truly are blocked, but that's not the issue I'm reporting, LOL)

Reproduction steps

Not sure how it starts. I believe making a change in tower orders may start it. The vehicles seem to want to return to the tower but think they can't get there for some reason...

Game version

0.5.1b

Attachments

Trucks stopping stuck.save

Files not imported: Trucks stopping stuck.save

Your trucks have no jobs to do, so they want to park next to their mine tower. However that tower is not accessible, it's on a hill and surrounded with retaining walls. Once that's restored it all works. So doesn't seem to be a bug there.

Closing as there are no action items left. Feel free to file a new bug if you have more info.