Thingsboard Integration: "error":"json: cannot unmarshal bool into Go value of type uint32","code":3

We are trying to send a downlink (RPC command from Thingsboard) to a RAK7431 end node. We could do it using the ‘external REST API’ call from the Thingsboard rule chain. However, we get “error”:“json: cannot unmarshal bool into Go value of type uint32”,“code”:3 while trying with integration downlink node in the rule chain. It seems the issue is with the Chirpstack. The downlink msg that we want to send is a Modbus RTU request to a relay, which is connected to the RAK7431 device:

         "confirmed": true,
        "data": "AgABAAgBBQAB/wDd+g==",
         "devEUI": "ac1f09fff*******",
         "fCnt": 0,
        "FPort": 129,
         "jsonObject": ""

The issue is with downlink only, we are able to receive uplink raw data from the RAK7431 device. How can we solve it?

Have you tried not setting the fCnt?

I tried it. The same error persists.

Upgrading the Thingboard version 3.2.2PE to version 3.3.2PE solved the problem.