Noble mining with broken primary - works but no yield it seems

If i see this right, Slimes here mines with a broken primary, and while the tiles still vanish (on the floor above), there is no yield from it...

The Foundry Barons.Save 151.octsav.gz

Edit: U usually see the stones lying on the lower floor then and there are none, there is some "earth" above, but yea, even when he mines stone above there is no drop.

Edit2: Gave him a working weapon, and after a nap he continued to mine that spot and still no drop, might be there was mostly earth above after all. He still shouldnt be able to mine without primary though, consistency to logging (they cant without prim)