1981 KZ440A - Guessing the Volatage Regulator is shot

Bike died just as I was about to leave the driveway. Pulled the plugs and had no spark but didn't have time to fiddle about so I put it on the battery charger for the day. Next day I had spark after the charge was complete. I started the bike and disconnected the batter + lead and it died (which I am learning now might be normal) so it seemed like an issue with the alternator. Tested the yellow lines with voltmeter from the stator and get 76V AC at 4000 RPM. Also checked voltage at battery which held solid at 12.23V DC no matter the RPMs. Tested the resistance across one of the yellow wires and the black wire coming from the regulator and got nothing (open circuit). Tested other yellow to black and same. Pulled a regulator off the parts bike and same result. Is this normal?

Your stator seems good.
I would just double check the wiring to the reg/rec.
The black is a ground wire. You will have an open between that and the yellow wires.

Grab your meter.
meter on DC V
bike running
all connectors connected

Black probe on negative battery post( post is the metal part of the battery)
Red probe on the positive battery post
Note voltage

Move the black probe to the black wire in the pink box( do not disconnect connector-back probe the connector).
Note voltage

Black probe back on negative battery post
Red probe on red/white wire in green circle
note voltage

Red probe on red wire in pink circle
note voltage

Just verifying your wiring

I guess I had to reseat the connectors because with the regulator unhooked the voltage slowly drops from 12.xx, when connected it starts to climb to about ~14-15 volts and stays. I just got so hung up on the manual saying there should be an ohm reading at the yellow and black that when I got no readings I figured it was a bad regulator. Took the bike out for a few hours and had no issues with it. Thanks for your help!