We were trying to phase out the general paint building for the more specialized building set. I cut off the input into the paint building since it had a supply of paint, and only a couple cars left.
Found that the individual phases (dry undercoat for example) don’t seem to advance if the machine can’t resupply the inputs. It would get to the end of dry undercoat, and then just start that phase over again. When we hooked it back up to the inputs more paint was ordered, delivered, and the production continued. This paint was not needed to do the painting.
I haven’t tried reproducing this with other buildings.