When connecting hot to ground, lights turn on. Open neutral?
So I solved this myself by tracing the wires.  I figured out that two circuits had shared a neutral when I found two open splices, traced them back and separated onto separate circuits.  I didn't realize it at the time. Once I traced the wires, drew out the diagram and figured out there was no neutral, I figured out where to connect the neutral back in to complete the circuit. All working now.


For posterity's sake, the original circuit diagram: