What? Pipes that are actually... underground!?
Small changes concerning balance, gameplay, or graphics.
Augmented or new ways of transporting materials - belts, inserters, pipes!
Things related to oil and other fluids.
This doesn't happen if I "pipette" an underground pipe. What I think is happening is the game discarding the pipes I have on my cursor when I change mode. The pipes lost aren't anywhere.
Fixed in latest release