LG French door fridge temp stays just below 50 no matter how low we set the temp. Freezer and icemaker are working perfectly.

Fridge is just about 6 years old, model lfxc24726s. Compressor was replaced in Dec 2020 due to complete cooling failure. They also replaced the motherboard then. All covered by LG.

This is what I have tried so far:

-I took out the inside back panels for both the fridge and freezer and there was no ice build up on either evap coil

- The fans all seem to be working fine. Confirmed visually that the ones in the fridge are ok, and also using the test button in the back panel/motherboard. Fan next to compressor also working fine.

- I vacuumed/blew out dust from the condenser coil but it was pretty clean to start with.

- I then let fridge sit open, unplugged for 24 hrs, though I didn’t see ice anywhere. As expected no water anywhere.

- Turned it back on and freezer/ice maker still working perfectly and fridge stuck just under 50F.

So, what to try next? - doesn’t look to be compressor or defrost issue.

Seems to be some communication issue between the temp set point on the door and feedback to the compressor. It holds temp well and consistent - but it is just below 50F.

Thermocouple/thermistor? Motherboard?