Summary:
These guys won’t mine this spot, they’re super lazy. I don’t think it’s that hard to just mine. C’mon, hearthlings.
I’ll attach my save file so you can see exactly what’s going on here.
Notes:
Here’s a visual illustration.
Also, whatever “bfs” is, it’s taking a colossal amount of my cpu.
Attachments:
Save file is attached.
1458495529235.zip (6.5 MB)
Version Number and Mods in use:
Steam latest, 537.
System Information:
Super fancy.
The only advice I could give you is to:
Didn’t see any mining bug, so @moderators
Huh. I did the pause/unpause, saved/reloaded, but I’d rather not cancel the task and redo it, because it’s still technically a bug. The more situations like this we send them, the better they can fix it. At least that’s my line of thinking.
BTW, BFS=Breadth first search
Basically, computers aren’t smart, if you want them to do anything they need to be instructed to. So if you tell a hearthling to mine, it’ll have no clue what to do. So it does a search on where to start mining (whatever that means) and it has to analyze the terrain to figure out where to begin. Or how to get there, out which of the squares to mine first. So it goes through at least some of the candidates, and makes a decision on what to do next. That is a search.
The Breadth first part just means it goes through tree tiers first, rather than down to the leaves.
What’s this particular search doing, I’m not sure. But just figured you’d like to know this much.
will try the save out 
they indeed did not go to work, suspend the mining and then restarting did not work. No error message. Only removing the task and replacing the area they needed to mine seemed to get them back to mining.
It seems to occure that tasks sometime break down. Only re-ordering it works.
I notice my people won’t work if certain tasks in the debug get stuck doing “something”.
“BFS” and “JOBKEEPING” constantly get locked in with everything else stuck at 0
I had a problem in the past if I overlapped mining orders they would completely ignore that mining area
FYI @Reyjakai and other, @albert is currently troubleshooting this issue on his end. No ETA, but he is aware and working on it 
!
I think I have a fix for this. If it passes playtesting, we’ll issue a patch. The fix might not help saved games, so you might need to re-zone one more time.
It’s no big deal, I just wanna make sure any inconsistencies in gameplay are made apparent so that you guys can remedy them. It isn’t going to pain me to click a few buttons.
Thanks for posting the save. It helped a lot!