i have indeed encountered it too. It is a bugg and quite the silly one…
Workers float in mid air after havind dugg away the ground below their feet.
Steps to reproduce:
- mine a hole in a mountain so that you have floating ground.
- tell your workers to mine the flaoting ground
Miners remove the ground and continue to do their job
some workers get stuck floaitng mid air since they have no place to go to. Because you dugg away the ground leading to any ladders and there is no ground to stand on they just go idle and die there…
You can work around it buy building a building so that they can get down again trough the saffolding or whatever.
I took the liberty of adding a bit more info for you @artifus