I had a similar problem. Old hardware (Emonbase RFM12Pi v2.6, EmonTX v3.2 RFM12B and first generation EmonTH). Although the radio seemed to be connected, I was not getting Temp and Humidity readings from the EmonTH. I pulled out the DHT22 module from the EmonTH and re-seated it a number of times. I visually checked all the soldering with a magnifying glass. I assumed the sensor moduel was broken and bought a new one. Still didn’t work. I got it working eventually…with switch cleaner and fine wire poking around into the connector receptacles. It had been sitting out under the porch for a few years and had developed some hidden residue or corrosion. I know your issue it not quite the same.
