Thanks to comments here and elsewhere on the forum I was able to figure it out. What wasn’t clearly stated or shown in any diagrams was how it should look with the C adapter in place. Since the original Y Wire from my old thermostat was going directly to the AC compressor and not to the air handler, I had to split that connection and connect the wire that goes to the AC compressor directly to the air handler as @speadie mentioned. Then put the Y wire coming from the thermostat to the Y port of the C adapter. I’ve attached a diagram showing the new wiring configuration. I reset the thermostat by pushing the button for 5 seconds and went through all the setup steps again. It’s working perfectly now.
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