I'm not familiar with the circuit or how it develops the field. Coming from a background in maintaining generators, it sounds like it's supposed to get battery voltage to flash the field and start generation.However the alternator didn’t start charging right away. It was as of the alternator wasn’t doing anything, verified by 11.2 volts at the battery.
After about 20 minutes it started charging like normal, and was fine on the drive after that.
If the battery voltage was weak, it may have struggled to flash the field. Or it may not be flashing the field at all and it took a while for the field to build up enough strength to begin generating. I've also heard of alternators that don't generate until you get them above a certain rpm.
You might try checking the voltage on startup and then seeing if you can get it to start generating by blipping the throttle to 3000+ rpm.
If it is a CS130 or CS144 as listed above, I'd jump straight to throwing a new voltage regulator on it. The diagram @1990Z71Swede posted clearly shows the voltage regulator controlling the field.