How to reproduce it:
- Begin a new game
- Place your settlement
- Open the building editor and trace a zone made of road
- Click on the firepit (editor will fade away)
- Choose move and place the firefit somewhere on the road zone (it will be visible)
Nothing happens
- Enter the building editor again
A ghost firepit is located where you tried to move it and cannot be removed. You can select it and eventually kill it via console.