CC2530 join stops without authentication

Hello everybody,

I’ve got a very special question. I am using zigbee2mqtt on a RasPi, together with a CC2531 USB dongle and koenkk’s firmware.

Now I try to join a CC2530, running TI’s original ProdHex firmware. I drive the CC2530, using the NWKTopoolgy example from the ZNP framework (and the framework itself, of course).
Unfortunately, the join does not succeed. It remains in the status “Joined but not yet authenticated by trust center”.
I sniffed the radio traffic, finding an “AssociationRequest” and a “Short Addr Assoc Status” as answer, followed by a bunch of “Data Requests”, but nothing that looks like a key or even encrypted data. zigbeeSheperd on DEBUG level only prints out a “tcDeviceInd” packet when the new device tries to join. Nothing else.

Since it is possible to pair other devices (Bulbs, xiaomi gadgets, etc.) the problem must be somewhere in my device. However, I have no idea how to continue from here. So if anybody could give me a hint what I could do to explore this further or even solve the problem, I would be most grateful.