New engine with no oil pressure.

I assume since you brought up the dreaded oil galley plug, you double checked that it is installed? But that said, yes. I have seen a new engine not have oil pressure. As stupid as it sounds, the builder stuffed the oil pump FULL of lubriplate white engine assembly grease. The rotors could not pull anything in to push it out, so we had to disassemble to investigate and that's what we found. Not that I would ever recommend doing that, but I actually couldn't believe that would stop a pump from pumping, but it dang sure did. We cleaned it all up and it buried a 100 PSI gauge on startup. It was a Mopar small block. A 340.