Alright, I have a number of nodes running.
One that had run before, I added the flag '--relax-fcnt'. It appeared in both MQTT (using node-red) and in the HTTP (http://thethingsnetwork.org/api/v0.1/nodes/...) once. Nothing since
Another one that had ran before, without the flag '--relax-fcnt'. It appeared once in both MQTT and the HTTP. After that it doesn't appear in the MQTT but the HTTP updates.