The “Invalid MIC” message appears when the LoRaWAN keys contained in the Join are different from those recorded in the sensor profile. The first thing to check is therefore that the LoRaWAN keys entered are the correct ones. On the other hand, it is possible that this message appears even when the LoRaWAN keys have been correctly entered, in this case, you would have to restart a Join and it should work, otherwise, if the problem persists, re-enter the appkey and restart a Join.