This is a bug linked to the mining bug but I don’t think it is the same.
When units are mining large sections they get hungry. They forget how to get to the food, and start to mine hangrly (hungry anger).
I am 4 ground levels directly beneath my food reserves.
Steps to reproduce:
Instamine 4 levels 40x40 chunks beneath the food reserve.
Then build floor/road on the space 40x40.
Units will starve themselves till the floor mining is complete, but not the tiling of the floor.