AC adapter measures 24V properly
Power GND to OG: 0.2mV
V+ to V- on each chip: about 1.3mV
IG to V+/V- on each chip: 0mV
OG to OR/OL: about 0mV
I was mistaken in the first post, it was the AD8620 LR chip getting hot, not the AD8610, and the going back and forth was probably me not having my leads pressed up against something correctly.
And I just realized I need to use the IR/IL/IG 2 for the pot I'm using, but that still doesn't solve the mystery of the non-lighting LED but the datasheet says the longer leg is the anode and that's what I have hooked up.