Thanks, mfalkvidd! Whaddya know, that was the problem...
Another thing I just thought of, is it correct to use send(temperatureMsg.set(temperature, 1)), etc., when the sensor is local, or is it treated by the gateway as any other remote sensor information coming in?
Seems like it is not sending much useful date to the MQTT broker either. This is what is send every minute (according to the serial monitor)
BME280 - Sensor module has some new values ready:
BME280 - Sending the new temperature to the gateway.
60093 GWT:TPS:TOPIC=mygateway1-out/0/1/1/0/0,MSG SENT
BME280 - Sending the new humidity to the gateway.
60106 GWT:TPS:TOPIC=mygateway1-out/0/2/1/0/1,MSG SENT
BME280 - Sending the new pressure to the gateway.
60116 GWT:TPS:TOPIC=mygateway1-out/0/3/1/0/4,MSG SENT
BME280 - Measurement complete. Going to wait until next measurement.
63579 GWT:TPC:IP=10.10.10.180
63582 GWT:RMQ:CONNECTING...
64290 GWT:RMQ:OK
64291 GWT:TPS:TOPIC=mygateway1-out/0/255/0/0/18,MSG SENT
64301 GWT:TPS:TOPIC=mygateway1-out/0/255/3/0/11,MSG SENT
64308 GWT:TPS:TOPIC=mygateway1-out/0/255/3/0/12,MSG SENT
64313 GWT:TPS:TOPIC=mygateway1-out/0/3/0/0/8,MSG SENT
64319 GWT:TPS:TOPIC=mygateway1-out/0/1/0/0/6,MSG SENT
64324 GWT:TPS:TOPIC=mygateway1-out/0/2/0/0/7,MSG SENT
So far I only have the log from the MQTT broker (Mosquito) to look at and it looks like a lot of the messages aren't arriving at the broker. I may have to set up a MQTT client to look at the actual messages to get a better look at what is going out from the gateway.