I reached out to the retailer in early September, and they have been unable to provide a replacement unit as they are on "backorder". Is it possible ...

Refrigerant valves are both fully open, and both inside and outside units are working.

No error codes nor any odd noises. My other 2 units work perfectly.

@eg4eric Correct, it's blowing room temperature air. Both high and low side lines are air temperature.

Any update to this? I'm having the exact issue with my just-installed EG4 12k.