Not really a bug and more than likely just an artifact of changing builds today. I had a section of previously built (3 real-time days ago) pathway disappear and now that section can’t be interacted with at all. It won’t let me rebuild, mine it or alter it in anyway. It just defaults to the “red X” cursor. Thought I should post it, just in case…please delete if Team Radiant thinks it’s irrelevant 
A close up of the section that disappeared. It’s a very crowded area, including tunnels underneath for water and close-proximity buildings
In relation to it’s surroundings, the missing section is at the tip of my mouse pointer
shallow cutaway showing footprint of surrounding builds and water
The layer 5 blocks below, where water passes under to fill my pool, this is where I think the problem actually happened and why I can’t alter it now. the section would be at the tip of my mouse again
Edit: I now see that my mouse didn’t show up in the screenshots. smacks forehead
The missing section is on the path between the brown roofed building and the blue roofed building…